Composers using electric bass include Christian Wolff (composer) (Electric Spring 1, 1966; Electric Spring 2, 1966/70; Electric Spring 3, 1967; and Untitled, 1996); Francis Thorne (Liebesrock 1968-69); Krzysztof Penderecki (Cello Concerto no. 1, 1966/67, rev. 1971/72; Capriccio for Violin and Orchestra (Penderecki), 1967); The Devils of Loudun (opera), 1969; Kosmogonia, 1970; and Partita (Penderecki), 1971); Louis Andriessen (Spektakel, 1970; De Staat, 1972-1976; Hoketus, 1976; De Tijd, 1980-81; and De Materie, 1984-1988); Pelle Gudmundsen-Holmgreen (Symfoni på Rygmarven, 1966; Rerepriser, 1967; and Piece by Piece, 1968); and Irwin Bazelon (Churchill Downs, 1970).
Question: What were all the years Christian Wolff changes electric spring?
Answer: 1966 | 1966/70 | 1967