MLA

Hughes, Langston, 1902-1967. Nichanov, Yusef. Box 470, folder 11623. n.d.. https://collections.library.yale.edu/catalog/2017004.

APA, 6th edition

Hughes, Langston, 1902-1967. (["Box 470, folder 11623"])(n.d.)[Nichanov, Yusef]. https://collections.library.yale.edu/catalog/2017004.