in service of a specific political and ideological agenda, commonly employing historical negationist methods. In the 1930s, historic archives were closed and original research was severely restricted. Historians were required to pepper their works with references – appropriate or not – to Stalin and other "Marxist-Leninist classics", and to pass judgment – as prescribed by the Party – on pre-revolution historic Russian figures. Many works of Western historians were forbidden or censored, many areas of history were also forbidden for research as, officially, they never happened. Translations of foreign historiography were often produced in a truncated form, accompanied with extensive censorship and corrective footnotes. For example, in the Russian 1976 translation of Basil Liddell Hart's History of the Second World War pre-war purges of Red Army officers, the secret protocol to the Molotov–Ribbentrop Pact, many details of the Winter War, the occupation of the Baltic states, the Soviet occupation of Bessarabia and Northern Bukovina, Western Allied assistance to the Soviet Union during the war, many other Western Allies' efforts, the Soviet leadership's mistakes and failures, criticism of the Soviet Union and other content were censored out. The Katyn massacre was formally assigned to Nazi Germany but the subject was frequently concealed. Soviet famines were taboo. Linguistics At the beginning of Stalin's rule, the dominant figure in Soviet linguistics was Nikolai Yakovlevich Marr, who argued that language is a class construction and that language structure is determined by the economic structure of society. Stalin, who had previously written about language policy as People's Commissar for Nationalities, read a letter by Arnold Chikobava criticizing the theory. He "summoned Chikobava to a dinner that lasted from 9 p.m. to 7 a.m. taking notes diligently." In this way he grasped enough of the underlying issues to oppose this simplistic Marxist formalism, ending Marr's ideological dominance over Soviet linguistics. Stalin's principal work in the field was a small essay, "Marxism and Linguistic Questions." Pedology Pedology was a popular area of research on the basis of numerous orphanages created after the Russian Civil War. Soviet pedology was a combination of pedagogy and psychology of human development, that heavily relied on various tests. It was officially banned in 1936 after a special decree of the Central Committee of the Communist Party of the Soviet Union "On Pedolodical Perversions in the Narkompros System" on July 4, 1936. Physics In the late 1940s, some areas of physics, especially quantum