MLA

Hulme, Kathryn, 1900-1981. Hepburn, Audrey. Box 17, folder 442. 1957-61. https://collections.library.yale.edu/catalog/17060831.

APA, 6th edition

Hulme, Kathryn, 1900-1981. (["Box 17, folder 442"])(1957-61)[Hepburn, Audrey]. https://collections.library.yale.edu/catalog/17060831.