MLA

Hughes, Langston, 1902-1967. Merriam, Eve. Box 111a, folder 2113. 1966 May 8. https://collections.library.yale.edu/catalog/17020435.

APA, 6th edition

Hughes, Langston, 1902-1967. (["Box 111a, folder 2113"])(1966 May 8)[Merriam, Eve]. https://collections.library.yale.edu/catalog/17020435.