MLA

Dunbar, Rudolph, 1899-1988. Barnet, Claude. Box 1, folder 5. 1964. https://collections.library.yale.edu/catalog/17029226.

APA, 6th edition

Dunbar, Rudolph, 1899-1988. (["Box 1, folder 5"])(1964)[Barnet, Claude]. https://collections.library.yale.edu/catalog/17029226.