MLA

Longstreet, Stephen, 1907-2002. Beginner brown/Early starter. Box 4, folder 19. 1939. https://collections.library.yale.edu/catalog/32458571.

APA, 6th edition

Longstreet, Stephen, 1907-2002. (["Box 4, folder 19"])(1939)[Beginner brown/Early starter]. https://collections.library.yale.edu/catalog/32458571.