Close encounters and flying saucers also have a place in socialist theory. The Posadists (supporters of Juan Posadas) in Latin America believed this concept was a logical extension of Marxist dialectical materialism. Posadas led a group of the Trotskyist Fourth International in Argentina. He was especially interested in the Chinese and Russian space programmes, and wrote a pamphlet in 1971 called La Ciencia Espacial. He envisioned the extension of the socialist revolution to outer space. Many pamphlets by Posadas and the Posadists can be consulted in the IISH library.