*Chapter 3
A Physiographic Characterization of the Study Area and the Nature of its Economic Development
Geographic Location: The position of the long-term study site is defined by the following coordinates: 45o00' -45o30' north latitude and 134o30'-135o00' east longitude. This area is located on the western macroslope of the Central Sikhote-Alin Mountains, and it can be represented schematically as a rectangle that is 40 km x 60 km (cf. Fig. 4). It includes the upper parts of the basins of the Malinovka River and the Orekhovka River (with its tributary, the Gornaya River). The valleys of these rivers are oriented approximately parallel to each other from east to west. Lower down in their courses (to the west of our sector), these rivers merge with their valleys converging in a fan-shaped pattern, changing from a broad expanse to a southerly (or nearly southerly) course. The Malinovka River is the largest left tributary of the Bol'shaya Ussurka River, flowing into it very close to mouth of the Bol'shaya Ussurka, i.e.,very close to the valley of the Ussuri River. The basin of the middle course of the Bol'shaya Ussurka River stretches to the north-east of the study region, while the Zhuravlevka River, a tributary of the Ussuri River, lies to the south of the study area.
Proceeding from east to west, the area of our observations is located at a distance of 150-170 km from the shore of the Sea of Japan and at a distance of 90-100 km from the valley of the Ussuri River. Analogous indices, measured along a line perpendicular to the expanse of the Sikhote-Alin Mountains as a whole, differ somewhat from those mentioned above: 120-150 km from the seashore (the shortest distance), and 90-110 km from the valley of the Ussuri River. In other words, our study area lies on the western periphery of the mountainous country of Sikhote-Alin, the main divide of which is located 80-100 km southeast of our site. Flowing westward over a distance of 50-70 km, the Malinovka River leaves behind the frontal ridges of the Sikhote-Alin Mountains and acquires the character of a river of the plains.
The Orekhovka and Gornaya Rivers get their start on the slopes of the Pervyi Pereval Ridge, which is small in extent, but orographically very distinctly expressed. The massif of the Mt.Zaoblachnaya which the Malinovka River bends around serves as its extension to the southwest. The Pervyi Pereval Ridge is one of several isolated mountain ridges (the Sinii, the Kholodnyi, and the Bogoladza) on the western periphery of the Sikhote-Alin Mountains that are divided by deep depressions that stretch almost linearly.
Topography: Despite the long-term study site being located within a system of regional mountain ridges of the Sikhote-Alin Mountains, its relief cannot possibly be characterized as piedmont. Nor can it be considered generally to contrast with the topography of the sector that adjoins the divide of this mountainous country. The district of interest to us is typical of all regions of the western macroslope of the Central Sikhote-Alin Mountains in its geomorphological relationship. Proceeding from the Pervyi Pereval Ridge to the main divide, a distinct tiered effect is not exhibited in the topography. Differences in elevation are insignificant, and they manifest themselves as very much a continuum. It suffices to say that the highest point of the long-term study area, which is located on the divide between the Orekhovka and Gornaya Rivers, is 1423 m above sea level, whereas the maximum elevation at that same latitude, which is that of the main divide, is 1598 m. above sea level. With regard to the differentiation in the relief and the steepness of the slopes, the region where we made our investigations also exhibits no essential differences from neighboring sectors of the western macroslope of the Sikhote-Alin Mountains. Differences are revealed only in a comparison with the eastern macroslope, where both the differentiation in the relief and the steepness of the slopes (and also the rockiness) are greater.
The length of the latitudinal sections of the valleys of the three rivers that intersect the study site is 35-45 km. The longest of them--the southernmost--is the Malinovka River, while the shortest--the middle one--is the Gornaya River. Here each of these rivers receives several large tributaries, the valleys of which extend for a distance of 12-15 km (the Malyi Klyuch and the Sobolikha) up to 20 km or more (the Igristyi, the Great Basin of the Gornaya River, the Bystraya). Besides them, the main rivers also receive a whole series of smaller tributaries that are 5-7 km in length (Bogdanov, Kolonkovyi, Khvoinyi Streams) or less. Mountain spurs, which divide the valleys of neighboring streams, are broken up by a complex system of "raspadky" (i.e., small side valleys that open into the main valley).
The valleys of the tributaries are usually oriented almost perpendicularly to the valley of the main river (the Komsomolka, the Valun, and the Ladoshina in the basin of the Malinovka River; the Malyi Klyuch, the Khvoinyi, and the Sobolikha in the basin of the Orekhovka River, etc.). More rarely, they are oriented at an acute angle to valley of the main river (the Bystraya in the basin of the Orekhovka River, and the Igristyi in the basin of the Gornaya River). Thus, the drainage as a whole has a typically "pinnate" structure. Since the valleys of the main rivers extend in a general orientation from east to west, their tributaries are oriented primarily from north to south or from south to north. The ridges are also oriented in a corresponding pattern. However, the system of smaller tributaries creates a very complex picture of the division of mountain ranges (which serve as watersheds), the spurs of which extend in the most varied directions. Distinctly marked valleys of the small streams lie at distances of 1-8 km from each other. Small side valleys can repeatedly replace each other even within a distance of 1 km. With the insignificant elevation of the mountains and the scarcity of distinctly salient peaks (and also as a consequence of the almost continuous forest cover of the slopes in a system of diversely branching spurs), second-degree divides often conceal more important orographic boundaries.
The density of the river network on the study site fluctuates within the range of 40-65 km per 100 km2. The valleys have a characteristic box-like profile with a distinctly expressed transition from the floodplain or the higher alluvial terrace levels to a slope. The flat bases of the valleys have varying widths (as measured from one rim to another). In the case of the main rivers in the long-term study site, this width ranges from 500-700 m to up to 1.5 km (occasionally up to 2 km). For the large streams, this width ranges from 200-400 m (less often up to 600 m); and in the case of small tributaries, this width is only tens of meters. The area of sectors of level relief along the valley bottoms (relative to the total area of the territory) is on the order of 20% (but not more than 25%).
As already noted, the maximum level for the absolute elevation equaled 1423 m above sea level for the region where our investigations were made. Only three peaks exceed an elevation of 1200 m, but "thousand-meter-high" mountains are relatively numerous. The minimum elevation--149 m above sea level--lies near the confluence of the Gornaya and Orekhovka Rivers. Thus, decreases in elevation of more than one thousand meters are characteristic of the territory under consideration, but its relief as a whole can be assessed as medium elevation. Relatively small elevational differences are, however, typical here. The divides of the main rivers lie within the range of 800-1000 m above sea level, and their branches, which occupy the main part of the territory, are situated even lower, in the range of 400-800 m above sea level. The relative elevation of mountain spurs with respect to the channels of the small streams usually does not exceed the limits of 200-350 m.
The steepness of the slopes fluctuates from 7-10o up to 30-35o, most often ranging from 15-25o. Slopes whose steepness exceeds 35o are only encountered in very limited areas; their relative extent is insignificant. On a scale of morphometric gradations, slopes of intermediate steepness are most characteristic of the long-term study site, although all variants, from "steeply sloping" to "steep", are represented here. In the majority of instances, the crests of the mountain spurs do not exhibit sharp gradients in elevation. Sometimes such crests are flattened-out over significant distance; it is easier to walk along them than it is to walk along the slopes. On the whole, the mountain ridges have gentle contours, and rocky massifs are few in number. Rocks are mainly confined to the steepest sectors of riparian slopes; they are occasionally also encountered on ridges of mountain spurs.
Rivers and Other Bodies of Water: No lakes exist in the territory under investigation. Swampy sectors are only encountered in a few places along the flood plains of rivers. Both the small streams and the larger rivers of the long-term study site are noted for their rapid currents and their numerous shoals. Rapids that run over rocks are, however, not characteristic of them. The width of the channels of the main rivers in the western section of the study area is 20-40 m, higher up on these rivers it is 10-20 m. During flooding due to summer rains, the level of the water in the rivers and streams rises rapidly. Even with precipitation that is average in amount, the rivers and streams overflow, submerging a low-lying floodplain. The rivers usually freeze over in the middle part of November, and the ice breaks up in the middle of April. The ice layer is, as a rule, covered with a layer of snow of greater or lesser depth. During January-February, the water often "eats away" the snow crust, and patches of pure ice form on the surface of the river channel. Channels in the floodplains of the rivers and streams appear in those places where subsurface waters ("teplyaki", or "warm springs") remain unfrozen even during severe frosts.
Climate and Wintering Conditions for the Animals: The general features of the climate of the Far East, which are determined by the monsoon circulation, are also present in the region where we made our observations: a warm, rainy summer, an extended dry autumn, and a frosty winter. In the Sikhote-Alin Mountains, however, the conditions of temperature, precipitation, wind, and other meteorological elements are subjected to significant local variations that at times manifest themselves even over a distance of several tens of kilometers. The montane topography and the influence of the sea, which rapidly weakens according to the degree to which one penetrates into the depths of the continent, are the causes of these differences. Local features of the climate in the long-term study area also are determined in the first place by its distance from the seashore (more than 100 km) and by the presence within this distance of orographic barriers (i.e., mountain ranges).
Information on the climatic conditions of the winter months is the most critical for the data presented below. In the first place, the data (which will be examined in later chapters of this book) were almost entirely collected during the winter. Secondly, for southern forms of mammals, to which group the tiger also belongs, it is precisely the conditions of the cold period of the year that can be considered as extreme. It is understandable that, from an ecological point of view, an analysis of these conditions is particularly important.
A network of meteorological stations does not exist within the boundaries of the territory under study. The nearest such station, Malinovka, is situated lower down on the course of the Malinovka River at a distance of 15-20 km. to the west of the nominal boundary of our study area. However, the data produced there can, apparently, be utilized to characterize the climatic features of the long-term study site without risk of significant error. The inclusion of the results of observations from two other, somewhat more distantly-located meteorological stations, Ust'-Kolumbe (located 40-50 km. to the north-northeast) and Zhuravlevka (situated 40-50 km. to the south-southwest) supplement this picture.
The average date (taken from a long series of annual observations) for the formation of a continuous snow cover is November 16 at the meteorological stations of Malinovka and Zhuravelevka, and it is November 14 for the Ust'-Kolumbe station. The destruction of the continuous snow cover, taken as the average for a series of years, occurs here on April 4-5. Thus, winter, if it is defined by the presence of a continuous snow cover, lasts approximately 4.5 months in the region where we made our investigations. Naturally, this time period fluctuates significantly depending on the elevation and on the slope's exposure at a given site. The temperature conditions of winter differ by their considerable severity--the mean temperatures of the months in question are much lower here than along the seashore.
For a series of observations made from 1951 to 19651, the temperature in mid-January (at 13:00 hrs) fluctuated from -13.3 to -18.9o C. at the Malinovka meteorological station and from -14.1 to -20.1o C. at Ust'-Kolumbe. The absolute winter minimum for the period indicated lies within the range of -36.4 to -45.9o C. (Malinovka) or -36.9 to -48.8o C. (Ust'-Kolumbe). We may note, for comparison, that, near the sea at almost the same latitude (Ternei Bay), the minimum winter temperatures are far from reaching those magnitudes: they ranged from -19.5 to -26.2o C. for the same period. Thus, severe frosts distinguish the districts on the western periphery of the Sikhote-Alin Mountains from coastal districts, and, at the same time, they make them similar to districts in Southern Siberia. This resemblance is not simply a superficial one: the severity of winter in both cases is determined by the influence of the Siberian anticyclone, which, in Primor'e, is opposed only by the warming influence of the sea. A strong insolation, an abundance of sunlight, characteristically accompanies the general predominance of clear, frosty weather in the winter season in the south of the Far East (Alisov 1956).
Strong winds, directed from the continent toward the sea, are a characteristic feature of the winter circulation of the atmosphere in Primor'e. If they reach significant strengths on the coast, then they are relatively weak on the western periphery of the Sikhote-Alin Mountains. Thus, according to data from the Malinovka meteorological station, the average monthly wind speed is 2.2 m/s in January and 2.3 m/s in February. For the southern part of the Far East, the wind speed in the winter is about 5 m/s on average (Alisov 1956). The average number of days per month in January and February with a strong wind (exceeding 15 m/s) is less than one at the meteorological stations of Malinovka and Zhuravlevka. In other words, a severe frost is accompanied here by a relatively weak motion, a stagnation of the air. The predominance of weather with weak winds and frequent calm periods is also a "Siberian" feature of the climate of our study area during the winter season.
1 Reference Book for the Climate of the USSR. Primorskii Krai. Meteorological Data for Individual Years: Air Temperature. Leningrad, 1971. No. 26. pt. 1. Pp. 247.
The number of days with solid precipitation is 561 for the entire cold period of the year, according to the Malinovka meteorological station. This means that snowfalls recur here on average more often than twice a week. The mean length of time in which precipitation falls, when added together for a given month, totals 69 hrs and 83 hrs for the months of February and March, respectively. In Dal'negorsk, which lies on the coastal macroslope of the Sikhote-Alin Mountains, only a short distance to the south of our long-term study area, the analogous figures are 26 hrs and 53 hrs (i.e., the durations of periods of snowfall are less by a factor of 2-3). Winter on the western periphery of the mountain country is not only one of more severe frosts, but it also has more snow.
The snow cover on the long-term study site usually reaches its greatest depth in the first ten-day period of March, but the entire period from the second ten-day period of January to the second ten-day period of March can be considered a time of much snow. The amount of snow fluctuates considerably from year to year. Thus, the greatest depth of snow cover for the entire winter (using a permanently-sited measuring gauge) equals 38 cm2 (on average) at Malinovka; the range of variation of this index for a series of years is 10-65 cm. The six-fold amplitude of variation is evidence of the alternation of winters with very little snow with those having a great deal of snow. According to data from the Malinovka meteorological station, a depth of snow cover of 30-50 cm recurs in the third ten-day period of February in more than half of the winters for which there is data.
Winters with the greatest depth of snow cover (over 40 cm) recur here 42% of the time, while at the Malinovka meteorological station, such winters recur 36% of the time. Thus, one should consider a level of snowfall in the winter in which the wintering conditions for mammals, in particular, the tiger, prove to be quite harsh to be typical of the study district.
The three winter seasons, over the course of which we conducted investigations of the ecology of the Amur tiger using the method of winter tracking, differ from each other in their meteorological features, in particular, in the depth of the snow cover. It is possible to use the data from regular snow measurements carried out by the Malinovka meteorological station and the meteorological station at Martynova Polyana(Table 3) to analyze these differences.For the period under consideration, the winters of 1970/71, 1971/72, and 1973/74 can be considered as winters of moderate snowfall. The winter seasons of 1969/70 and 1972/73 are noted as the ones having the greatest depth of the snow cover. During these same winters, there was a sharp rise in the length of time when the depth of the snow cover remained at a level that was close to the yearly maximum. Thus, by the third ten-day period of December, 1972, a snow layer of more than 40 cm in depth already lay along the valleys of the streams.
1 Reference Book for the Climate of the USSR. Primorskii Krai. Humidity, Atmospheric Precipitation, Snow Cover. Leningrad, 1968. No. 26. Pp. 237
2 The area where the main observations were made is located at a significantly greater absolute elevation, and the corresponding indices are higher there.
Table 3:
Characteristics of the Snow Cover in our Study District for Five Winter Seasons
(Source: Meteorological Almanacs for 1969-1974)
Date
Greatest Depth of Snow Cover (cm)
Period of Maximum Accumulation of Snow
Malinovka Meteorological Station
Martynova Polyana Meteorological Station
Malinovka Meteorological Station
Martynova Polyana Meteorological Station
1969/70 54 68 February-middle of the 3rd 10-day period of March
February-3rd 10-day period of March
1970/71 33 52 3rd 10-day period of February- middle of the 2nd 10-day period of March
3rd 10-day period of February-2nd 10-day period of March
1971/72 30 48 End of the 3rd 10-day period of February-1st 10-day period of March
2nd 10-day period of February-1st 10-day period of March
1972/73 40 54 3rd 10-day period of January-middle of the 3rd 10-day period of March
February-3rd 10-day period of March
1973/74 30 52 2nd 10-day period of February-1st 10-day period of March
2nd 10-day period of February-2nd 10-day period of March
The depth of the snow cover is not the same at different absolute elevations or in different types of forest. At the end of December, 1972, an increase in this index of 20 cm was traced from the valleys to the ridges; on December 24, snow that was 65 cm in depth was present on a ridge at an elevation of approximately 900 m above sea level . Similar differences were also noted due to a smaller change in elevation. For example, on January 11, 1980, when the snow lay at a depth of 30-32 cm at an elevation of 240 m above sea level in the valley of the Gornaya River, the snow layer reached a depth of 45 cm at an elevation of 480 m in the upper reaches of Evseeva Stream. In the habitats of the tiger, the greatest changes in the snow conditions can be traced from the dense coniferous timber stands to open spaces; scarce deciduous timber stands occupy an intermediate place between these two extremes. In actual cases, where the depth of the snow cover reached 40-50 cm on open sites, it did not exceed 25-30 cm under a canopy of spruce (Picea spp.) trees.
Conditions for the travel of animals over snow depend to a great degree on the availability of a snow crust. At the end of winter, the snow thaws at its fastest rate, settles, and becomes covered with a strong crust on south slopes, and the same thing later occurs in the valleys. Snow still remains friable for a long time on northern slopes. A snow crust usually forms beginning in the second half of February on our study site, lasting through all of March and part of the month of April. A strong snow crust easily supports a man on skis. At certain periods, even tigers and bears are able to travel freely on top of it without sinking in (observations of April 7-12, 1973). Rain, which sometimes falls during winter thaws, can also cause the ubiquitous formation of an ice crust. We noted the latest date for rainfall to be November 24, and the earliest rainfall date was February 17, 1973. Rainfall is already frequent by March and April.
Vegetation: The area of the long-term study site is almost entirely covered by a continuous forest canopy. The main type of forest formation is Korean pine (Pinus koraiensis)-broadleaved forest, which has now been disturbed by man to a greater or lesser extent. Spruce-fir taiga does not form a unified zone and is encountered as small, isolated stands on the upper reaches of streams and on large mountain peaks. ('podgol'tsoviye') [kinds of vegetation that typically grow in a zone directly below the mountain peaks] groupings of vegetation cover are represented here in a still more fragmentary manner.
B. P. Kolesnikov (1956) divided the range of distribution of forests containing Korean pine into three parts: northern, central, and southern. Our study district belongs to the central part, where conditions for the establishment of the Korean pine-broadleaved forests are optimal. The elevations of the mountain ranges and spurs that predominate on the long-term study site also favor the development of precisely this forest formation, since a continuous belt of Korean pine develops only up to an elevation of 500-600m above sea level.
Korean pine stands with oak (Quercus spp.) are the most characteristic of steep, southern slopes; forests growing on slopes with a northern exposure are distinguished by having a significant admixture of spruce and fir (Abies), particularly in the subcanopy and the undergrowth. Korean pine forests with dark coniferous tree species are also found on terraces near foothill slopes where a twisted and dense fir stand is often found. As a whole, the valleys of the rivers and streams are distinguished by a predominance of Korean pine-deciduous forests of the most diverse composition and complex structure, often with dense undergrowth. Sectors of flood-plain forests [of poplar (Populus), elm (Ulmus), ash (Fraxinus), and willow (Salix)] are confined to areas where the valleys broaden; Korean pine is also almost always present everywhere in these stands, but only as an admixture.
Pure stands of oak are locally encountered along steep, southern slopes on sections of the lower courses of rivers that cross the long-term study site. They are found near the settlement of Martynova Polyana, rising as single stands upward along the Gornaya River up to Kammenyi Stream. Large stands of secondary parvifoliate (i.e., small-leaved) forests are not present on the territory where tracking was conducted. Larch (Larix) forests are also almost absent here--both in the valley habitats as well as on the mountain slopes.
Nature of Economic Development in the Territory: The information on the ecology of the Amur tiger that is present in the literature pertains, to a significant degree, to nature reserves. Since the conservation of the tiger cannot be ensured solely by nature reserves, an evaluation of the conditions already existing and the prospects for the existence of the tiger on non-protected territories acquires particular significance. Our investigations envisioned the solution of precisely this problem, for which reason a sector of a natural complex that experiences the effects of man in ways and directions that are typical of the Central Sikhote-Alin Mountains was selected for long-term study.
The main type of economic activity in the district is logging, which takes place on approximately 70% of the territory. The basins of the majority of streams here have repeatedly been subjected to logging. By the time we began our observations, logging roads had been laid down along practically all the rivers and full brooks of the long-term study site (almost everywhere with the exception of only the steepest slopes), for harvesting Korean pine forests. They selectively harvested mainly Korean pine and, later, ash. Naturally, open felling areas are not present on sites with this kind of timber cutting. The slopes are not denuded of vegetation. The forest cover preserves its continuity, and frequently also maintains a sufficiently high connectivity of the canopy. The differences between sectors that have undergone cutting and undisturbed taiga reduce to, in first place, a greater degree of "cluttering up" of such places with an undergrowth and a noticeable thinning of the timber stands. The latter, as well as the availability of skidding transport, serves as the cause of the fact that it becomes easy to look through such forests. Over time, almost impassable thickets of aralia (Aralia spp.) and magnolia vine (Schizandra) develop on the skidding roads.
With respect to the spruce-fir taiga, which occupies a relatively small area in the upper zone of the mountains on the observation site, these forests have not suffered from cutting to any significant extent.
As has already been mentioned, the network of logging roads in the study district is fairly dense: its structure corresponds almost completely with a map of the hydrographic network. The roads diverge from the valley of the main river in the narrow side valleys of its tributaries and extend toward the upper reaches of the river. Also, roads do not cross the divides of the main rivers of the district (the Orekhovka, the Gornaya, and the Malinovka). There is only a track going across the mountain pass into the basin of the Bol'shaya Ussurka River. Since the sites where logging takes place move from year to year, only some of the roads (not more than half of their total length) are exploited during the course of a given winter. Transport is practically absent on the remaining roads. Here, it is not uncommon also to find roads that have become overgrown due to having been unused for many years.
The flow of traffic is insignificant even on actively used roads. Logging takes place primarily in the morning and in the evening; solitary vehicles pass during the day. Night transport of timber is practiced only exceptionally. At night almost all the roads therefore remain "at the complete disposal" of the tigers.
During the years when we made our observations, logging was carried out in only a few places within the long-term study area. Thus, along the basin of the Gornaya River, there were not more than two (and in total for the district of our observations--not more than six) such sites. On an active felling area, groups that total 20-30 people are present during the day along with up to ten units of machinery [skidding tractors, loaders, etc.]. At the end of the working day, the people are brought to a settlement in buses. On the territory, where the work was primarily conducted, there are only three small (on the order of a hundred houses) settlements; two settlements that are larger are located well beyond its boundaries. The area of agricultural lands relative to the total area of the long-term study site is insignificant in amount. Only vegetable gardens and small hay fields, which are strictly confined to the river valleys, exist in the vicinity of the settlements of Belokamennoe, Polyany, and Martynova Polyana. There are small fields (with a total area of up to 500 hectares) near the settlements of Pozhiga and Ariadnoe along the Malinovka River. The number of cattle in the settlements that are situated along the Orekhovka and Gornaya Rivers, amounts to only a few tens of animals; the cattle are pastured at a distance of not more than 5-10 km. from inhabited sites.
Fur trapping is carried out in winter on the majority of the territory where we made our observations. Here there are about 25 hunting shacks (winter quarters), of which a portion are not utilized due to their dilapidated condition. Neighboring habitable winter quarters are usually separated from each other by a distance of more than ten kilometers; they are scattered throughout almost all of the long-term study area. Fur trapping is carried out both by state hunters and also by amateur hunters. Along the basins of the Gornaya and Orekhovka Rivers, for example, 15-20 people hunt, the majority of them spending only the first months of the hunting season--November through December--in the taiga. Later, it is mainly just a few state hunters who remain in the forest. Taiga located far from settlements is almost never visited by humans after the end of this fur-trapping season. The main focus of the industry is the capture of the Siberian ferret (Mustela sibirica) and the American mink (Mustela vison) with leg traps and the shooting of squirrels (Sciurus spp.). Hunting of squirrels is carried out, as a rule, without the use of dogs. Therefore, even at the height of the fur industry season , only a few individual dogs are found in the long-term study area. Individual hunters carried out the systematic preparation of meat of wild ungulates during the years of our study (and this was done mainly in conjunction with the hunt for fur-bearing animals). Only once during this time was an attempt at an organized harvest of ungulates undertaken by a team of hunters along Igristye Stream. On the territory where the tracking was conducted, there are quite a lot of artificial salt licks (natural ones are not present). There are approximately 15 such salt licks in the basin of the Gornaya River alone. In the summer, cases of poachers shooting Manchurian red deer (Cervus elaphus xanthopygos) are not uncommon here.
In the years that have passed since the completion of our fieldwork, much has changed on the territory of our former long-term study site, but as regards the analysis of the data collected by us, these changes are unimportant.
Copyright Ώ A. G. Yudakov,I. G. Nikolaev
Copyright Ώ K. Lofdahl, A. Shevlakov, 2004 (English translation)