MLA

Bullitt, William C. (William Christian), 1891-1967. Arrival. Box 180, folder 8. 1933 December. https://collections.library.yale.edu/catalog/10016012.

APA, 6th edition

Bullitt, William C. (William Christian), 1891-1967. (["Box 180, folder 8"])(1933 December)[Arrival]. https://collections.library.yale.edu/catalog/10016012.