MLA

Van Vechten, Carl, 1880-1964. Bubbles, John W., as Sportin' Life in Porgy and Bess, musical composed by George Gershwin, libretto by DuBose Heyward and Ira Gershwin. Box 86 | Folder 1444. 1935 December 27. https://collections.library.yale.edu/catalog/2021399.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 86 | Folder 1444"])(1935 December 27)[Bubbles, John W., as Sportin' Life in Porgy and Bess, musical composed by George Gershwin, libretto by DuBose Heyward and Ira Gershwin]. https://collections.library.yale.edu/catalog/2021399.