"Entered from booking ledger and New York Times concert listing and review.\r\nNEW YORK PREMIERE of Henk Badings' SONATA FOR SOLO VIOLIN\r\n\"CONCERT AND OPERA PROGRAMS FOR THE WEEK.\" New York Times (1923-Current file), Oct 14 1956, p. 1. ProQuest. Web. 5 Apr. 2021.\r\n\"KOOPER, VIOLINIST, SCORES IN DEBUT: INSTRUCTOR AT PEABODY HEARD AT CARNEGIE RECITAL HALL-- WIFE IS ACCOMPANIST.\" New York Times (1923-Current file), Oct 21 1956, p. 85. ProQuest. Web. 5 Apr. 2021." . . . . "duo recital" . "1956-10-20T17:30:00"^^ . . "Kees Kooper, Violin, and Mary Louise Boehm, Piano" . . . . . .