MLA

Pratt, Richard Henry, 1840-1924. Miscellaneous and unidentified, 3 items. Box 23a, folder 751. n.d.. https://collections.library.yale.edu/catalog/2041182.

APA, 6th edition

Pratt, Richard Henry, 1840-1924. (["Box 23a, folder 751"])(n.d.)[Miscellaneous and unidentified, 3 items]. https://collections.library.yale.edu/catalog/2041182.