MLA

H. D. (Hilda Doolittle), 1886-1961. Gray, Cecil. Box 10, folder 345. 1918. https://collections.library.yale.edu/catalog/17064191.

APA, 6th edition

H. D. (Hilda Doolittle), 1886-1961. (["Box 10, folder 345"])(1918)[Gray, Cecil]. https://collections.library.yale.edu/catalog/17064191.