1. Interview with George Humphreys, 4 September 1981; transcript in possession of author
2. Expenses: 1929–1937, Box 10, Apgar Papers, Mt. Holyoke College Library/Archives (AP-MHCLA)
3. Personal diary: Box 10, AP-MCLHA
4. Matthew C. Fleming to Apgar, 15 June 1938: Box 4, Folder 21, AP-MHCLA
5. Interview with Belmont and William Musicant, 6 June 1981: transcript in possession of author