MLA

McKay, Claude, 1890-1948. Johnson, James Weldon. Box 4, folder 118-122. 1928-40, n.d.. https://collections.library.yale.edu/catalog/17398642.

APA, 6th edition

McKay, Claude, 1890-1948. (["Box 4, folder 118-122"])(1928-40, n.d.)[Johnson, James Weldon]. https://collections.library.yale.edu/catalog/17398642.