MLA

Pratt, Richard Henry, 1840-1924. "Di-Du" general, 19 items. Box 2, folder 67. 1876-1921. https://collections.library.yale.edu/catalog/10081322.

APA, 6th edition

Pratt, Richard Henry, 1840-1924. (["Box 2, folder 67"])(1876-1921)["Di-Du" general, 19 items]. https://collections.library.yale.edu/catalog/10081322.