1973
1973 - Elliot Schwartz, A listener's guide, Electronic Music; Praeger; NY 1973, pp.139-40; 160-161

https://archive.org/details/electronicmusicl00schw#:~:text=by%20Schwartz%2C%20Elliott%2C%201936%2D,4740%2D431e%2Db186%2D9b9351f397c0