MLA

Wat, Aleksander, 1900-1967. Documents (various). Box 35, folder 786-789. 1941-1967. https://collections.library.yale.edu/catalog/10050142.

APA, 6th edition

Wat, Aleksander, 1900-1967. (["Box 35, folder 786-789"])(1941-1967)[Documents (various)]. https://collections.library.yale.edu/catalog/10050142.