Entered from booking ledger and New York Times concert listing and review. The review does not mention the Manhattan String Quartet, so that group's participation is surmised. "Who Makes Music and Where: METROPOLITAN OPERA." New York Times (1923-), 18 Jan. 1970, p. 95. ProQuest. Web. 25 June 2025. "RALPH STANG OFFERS AMBITIOUS PROGRAM." New York Times (1923-), 23 Jan. 1970, p. 26. ProQuest. Web. 25 June 2025.