MLA

Hughes, Langston, 1902-1967. Armstrong, Louis. Box 8, folder 183. n.d.. https://collections.library.yale.edu/catalog/33219451.

APA, 6th edition

Hughes, Langston, 1902-1967. (["Box 8, folder 183"])(n.d.)[Armstrong, Louis]. https://collections.library.yale.edu/catalog/33219451.