MLA

Hughes, Langston, 1902-1967. Lincoln, Abbey. Box 469, folder 11576. n.d.. https://collections.library.yale.edu/catalog/33548811.

APA, 6th edition

Hughes, Langston, 1902-1967. (["Box 469, folder 11576"])(n.d.)[Lincoln, Abbey]. https://collections.library.yale.edu/catalog/33548811.