MLA

Van Vechten, Carl, 1880-1964. Waters, Ethel, as Hagar in Mamba's Daughters, play by Dorothy Heyward and DuBose Heyward. Box 108, folder 1968. 1939 February 19. https://collections.library.yale.edu/catalog/2028419.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 108, folder 1968"])(1939 February 19)[Waters, Ethel, as Hagar in Mamba's Daughters, play by Dorothy Heyward and DuBose Heyward]. https://collections.library.yale.edu/catalog/2028419.