MLA

Toomer, Jean, 1894-1967. "Sequences": notes and drafts. Box 48, folder 1013. n.d.. https://collections.library.yale.edu/catalog/16725534.

APA, 6th edition

Toomer, Jean, 1894-1967. (["Box 48, folder 1013"])(n.d.)["Sequences": notes and drafts]. https://collections.library.yale.edu/catalog/16725534.