Compositions   1951: Concerto for Prepared Piano 1952: 4' 33" 1958: Piano Concerto 1960: Cartridge Music 1969: HPSCHD 1972: Bird Cage 1981: Thirty Pieces for Five Orchestras	World Politics 1949: Mao declares Chinese Republic       1961: Berlin Wall built   1975: End of Vietnam War   1991: Soviet Union disbanded