MLA

Hughes, Langston, 1902-1967. Lampkin, Charles. Box 469, folder 11570. 1949, 1951, n.d.. https://collections.library.yale.edu/catalog/33548852.

APA, 6th edition

Hughes, Langston, 1902-1967. (["Box 469, folder 11570"])(1949, 1951, n.d.)[Lampkin, Charles]. https://collections.library.yale.edu/catalog/33548852.