MLA

Johnson, James Weldon, 1871-1938. Bennett, Gwendolyn. Box 3, folder 44. 1938, undated. https://collections.library.yale.edu/catalog/16747975.

APA, 6th edition

Johnson, James Weldon, 1871-1938. (["Box 3, folder 44"])(1938, undated)[Bennett, Gwendolyn]. https://collections.library.yale.edu/catalog/16747975.