MLA

Johnson, James Weldon, 1871-1938. from J. Rosamond Johnson. Box 42, folder 38. 1910-54, undated. https://collections.library.yale.edu/catalog/17397032.

APA, 6th edition

Johnson, James Weldon, 1871-1938. (["Box 42, folder 38"])(1910-54, undated)[from J. Rosamond Johnson]. https://collections.library.yale.edu/catalog/17397032.