MLA

Purdy, Richard Little, 1904-1990. Notes: 1935 trip to Europe, re: conversations with Florence Hardy, with itinerary. Box 20, folder 628e. 1935 Aug. https://collections.library.yale.edu/catalog/16482209.

APA, 6th edition

Purdy, Richard Little, 1904-1990. (["Box 20, folder 628e"])(1935 Aug)[Notes: 1935 trip to Europe, re: conversations with Florence Hardy, with itinerary]. https://collections.library.yale.edu/catalog/16482209.