Sergey Mstislavsky  Sergey Dmitrievich Mstislavsky (Серге′й Дми′триевич Мстисла′вский, born Maslovsky; November 4, 1876, Moscow - April 22, 1943, Irkutsk, USSR) was a Russian Soviet writer, dramatist, publicist, anthropologist, editor and political activist, close to the Left Socialist-Revolutionaries. In the 1920s and 1930 he authored numerous adventure novels, mostly about the events of the 1905 and 1917 Revolutions and the Russian Civil War ("Built on Blood", 1927; "The Heavy Cavalry Alliance", 1928; "The Partions", 1932; "The Eve. 1917", 1937). Sergey Maslovsky was born in Irkutsk, to a professor of the Russian military academy. He studied natural sciences in Saint Petersburg University which he graduated in 1901. While a student he took part in several expeditions to the Central Asia; as a result, the series of stories and sketches ("On the Margins", "In Samarkand", "Kop-Kara" and others) came out in 1900. In 1904 Mstislavsky joined the Left Socialist-Revolutionaries and took part in the 1905 Revolution. He became the Fighting Workers' Union chairman, then one of the leaders of the All-Russian Officers' Union. In 1910 he was imprisoned and spent a year in the Petropavloskaya Fortress. In the 1900s he published several books on anthropology and bibliography ("Galtcha", 1901; "The Bibliography of Afghanistan", with V.F.Goetse and B.P.Kareev; "The Military Press Archives", 1911). Mstislavsky (now known under this pseudonym) took part in the February Revolution. In October 1917 he worked in Smolny, and was a member of the 2nd All-Russian Congress of the Soviets. As a commissar for the Petrograd Soviets he was in the team sent to arrest Nicolas II. After the murder of Ambassador Wilhelm von Mirbach he quit the Left SRs and joined the Ukrainian Borotbists Party, which he left in 1921. After the end of the Russian Civil War Mstislavsky worked in publishing. He was one of the editors of The Great Soviet Encyclopedia (2nd edition). In 1925 Mstislavsky's first novel "Roof of the World" was published, based on his sketches and essays written in the 1900s and based on his Central Asian expeditions.