MLA

H. D. (Hilda Doolittle), 1886-1961. McAlmon, Robert. Box 54, folder 1379. n.d.. https://collections.library.yale.edu/catalog/2044060.

APA, 6th edition

H. D. (Hilda Doolittle), 1886-1961. (["Box 54, folder 1379"])(n.d.)[McAlmon, Robert]. https://collections.library.yale.edu/catalog/2044060.