1. Letter from Severo Ochoa to Maxine Singer Creator: Ochoa, Severo, 1905-1993New York University. College of Medicine Date: 11 November 1957 Genre: Letters (correspondence)
2. Letter from Severo Ochoa to Maxine Singer Creator: Ochoa, Severo, 1905-1993New York University. College of Medicine Date: 24 May 1958 Genre: Letters (correspondence)