MLA

Beckford, William, 1760-1844. Beckford, Susan. Box 1, folder 4-5. 1805-08. https://collections.library.yale.edu/catalog/16470620.

APA, 6th edition

Beckford, William, 1760-1844. (["Box 1, folder 4-5"])(1805-08)[Beckford, Susan]. https://collections.library.yale.edu/catalog/16470620.