MLA

Johnson, James Weldon, 1871-1938. Edwards, Agnes. Box 104, folder 888. circa 1900. https://collections.library.yale.edu/catalog/16794055.

APA, 6th edition

Johnson, James Weldon, 1871-1938. (["Box 104, folder 888"])(circa 1900)[Edwards, Agnes]. https://collections.library.yale.edu/catalog/16794055.