MLA

Purdy, Richard Little, 1904-1990. Biographical article on Thomas Hardy, typescript, corrected. Box 1, folder 7. [ca.1900]. https://collections.library.yale.edu/catalog/16482195.

APA, 6th edition

Purdy, Richard Little, 1904-1990. (["Box 1, folder 7"])([ca.1900])[Biographical article on Thomas Hardy, typescript, corrected]. https://collections.library.yale.edu/catalog/16482195.