Historians may at last have the document they need to determine the number of victims lost in the Stalinist repressions and in World War II.A new book, titled "The 1939 Census: Basic Results," which has just been published by the Nauka press, will provide researchers with previously unpublished material on the population of the Soviet Union in the crucial period between the height of the purges --1937 -- and the beginning of World War II in 1941.Yury Polyakov, director of the Center for Territory and Population at the Institute of Russian History, who edited the book, said it would be an invaluable aid to students of the period. "Without this book, any study of the history of the 1930s and 1940s is impossible," he said.The 1939 census is of particular interest to historians, because it fills in a 30-year gap: A population count was conducted in 1926, showing the population of the Soviet Union to be 140 million. Another census was taken in 1937, but the results were never published. After 1939, no new population count was taken until 1959.According to Murray Feschbach, a specialist in Soviet demography at Georgetown University in Washington, D.C., Stalin disliked the 1937 figures, declared that the results had been falsified and had the directors of the statistical committees arrested.The 1939 census was conducted to compensate for the "defective" one of 1937, Polyakov said. Stalin had stated on numerous occasions during the early 1930s that the population of the Soviet Union was growing at a rate of more than 3 million persons per year. This meant that the population count in 1939 should have been approximately 180 million, building on the 1926 results.The 1939 census showed a population of 170 million, a shortfall of 10 million, and even that count was most likely falsified, Feschbach said. Despite the unsatisfactory results, the final tabulation was released. But no additional information -- age, sex, education, regional distribution -- was published."The Soviet Union did not want to give Germany any data on prospective fighting forces," said Feschbach. "And the results that were released were suspect."The next census, in 1959, came well after the territorial changes and population dislocations caused by the war. Lacking the data from the 1939 poll, historians have had a difficult time trying to determine exact figures for the tremendous losses suffered by the Soviet Union during the purges of the 1930s and the devastation of the war years.Polyakov cautions that the new book gives no magic answers to these questions."History is not a sleeping beauty, to be awakened by the kiss of one special document," he said. "It will take careful analysis and a comparison of numerous sources to come up with figures."Polyakov's estimates of purge victims are more conservative than other figures cited -- from Feschbach's 10 to 12 million to counts of 20, 30, even 60 million cited by others, including Alexander Solzhenitsyn in his mammoth chronicle of the prison camps, "The Gulag Archipelago.""None of those figures have any scientific basis," said Polyakov. "There was a 'special census' of the prisons and camps, that showed approximately 3 million inmates. But no distinction was made between criminals and political prisoners. Another 1 million were certainly shot. But the total is still nowhere near 20 million."