MLA

Hughes, Langston, 1902-1967. Adams, Adele. Box 2, folder 28. 1956. https://collections.library.yale.edu/catalog/32604353.

APA, 6th edition

Hughes, Langston, 1902-1967. (["Box 2, folder 28"])(1956)[Adams, Adele]. https://collections.library.yale.edu/catalog/32604353.