MLA

Pratt, Richard Henry, 1840-1924. Carlisle School, 3 items. Box 23, folder 726. n.d.. https://collections.library.yale.edu/catalog/2001749.

APA, 6th edition

Pratt, Richard Henry, 1840-1924. (["Box 23, folder 726"])(n.d.)[Carlisle School, 3 items]. https://collections.library.yale.edu/catalog/2001749.