MLA

Thayer, Scofield, 1889-1982. Williams, William Carlos. Box 8, folder 280-287. 1922-29. https://collections.library.yale.edu/catalog/17142289.

APA, 6th edition

Thayer, Scofield, 1889-1982. (["Box 8, folder 280-287"])(1922-29)[Williams, William Carlos]. https://collections.library.yale.edu/catalog/17142289.