MLA

Hughes, Langston, 1902-1967. Cunard, Nancy. Box 49, folder 918-920. 1934-63, n.d.. https://collections.library.yale.edu/catalog/10189518.

APA, 6th edition

Hughes, Langston, 1902-1967. (["Box 49, folder 918-920"])(1934-63, n.d.)[Cunard, Nancy]. https://collections.library.yale.edu/catalog/10189518.