MLA

Hughes, Langston, 1902-1967. Bair, Fred. Box 12, folder 251. 1928, n.d.. https://collections.library.yale.edu/catalog/33412697.

APA, 6th edition

Hughes, Langston, 1902-1967. (["Box 12, folder 251"])(1928, n.d.)[Bair, Fred]. https://collections.library.yale.edu/catalog/33412697.