"Great Soviet Encyclopedia (EF)" is one of the largest and most authoritative reference books in the world, which was published in the USSR in 1926-1990. A total of 61 volumes, including 2 additional ones, cover a wide range of topics, from history and politics to science, culture, art and technology. Each article in the encyclopedia was prepared by the leading specialists of its time, which guarantees the high quality and reliability of the materials provided. "Great Soviet Encyclopedia (EF)" has become a real treasure for everyone who is interested in science, culture and history of the Soviet Union.