MLA

Hughes, Langston, 1902-1967. Spencer, Kenneth. Box 471, folder 11706. 1957 n.d.. https://collections.library.yale.edu/catalog/17394796.

APA, 6th edition

Hughes, Langston, 1902-1967. (["Box 471, folder 11706"])(1957 n.d.)[Spencer, Kenneth]. https://collections.library.yale.edu/catalog/17394796.