Shortly after his release from Görlitz in May 1941, Messiaen was appointed a professor of harmony at the Paris Conservatoire, where he taught until his retirement in 1978. He compiled his "Technique de mon langage musical" ("Technique of my musical language") published in 1944, in which he quotes many examples from his music, particularly the Quartet. Although only in his mid-thirties, his students described him as an outstanding teacher. Among his early students were the composers Pierre Boulez and Karel Goeyvaerts. Other pupils included Karlheinz Stockhausen in 1952, Alexander Goehr in 1956–57, Tristan Murail in 1967–72 and George Benjamin during the late 1970s. The Greek composer Iannis Xenakis was referred to him in 1951; Messiaen urged Xenakis to take advantage of his background in mathematics and architecture in his music.