MLA

Beckford, William, 1760-1844. Gore, Catherine. Box 2, folder 19. [1839?]. https://collections.library.yale.edu/catalog/16470621.

APA, 6th edition

Beckford, William, 1760-1844. (["Box 2, folder 19"])([1839?])[Gore, Catherine]. https://collections.library.yale.edu/catalog/16470621.