Entered from booking ledger and New York Times concert listing and review. "CONCERT AND OPERA PROGRAMS FOR THE WEEK." New York Times (1923-Current file), Apr 28 1957, p. 1. ProQuest. Web. 28 July 2021. "Margarita De Ferran Sings." New York Times (1923-Current file), May 03 1957, p. 20. ProQuest. Web. 3 Aug. 2021.