MLA

Bryher, 1894-1983. "For Marianne": typescript, original. Box 91. n.d.. https://collections.library.yale.edu/catalog/17290864.

APA, 6th edition

Bryher, 1894-1983. (["Box 91"])(n.d.)["For Marianne": typescript, original]. https://collections.library.yale.edu/catalog/17290864.