Entered from booking ledger and New York Times concert listing and review.
"PROGRAMS OF THE WEEK." New York Times (1923-Current file), May 26 1957, p. 1. ProQuest. Web. 25 Aug. 2021.
"ISOBEL WALTERS SINGS: SOPRANO DISPLAYS POISE AND ASSURANCE AT RECITAL." New York Times (1923-Current file), May 29 1957, p. 25. ProQuest. Web. 30 Aug. 2021.