MLA

Pratt, Richard Henry, 1840-1924. Bonnin, Gertrude S., 4 items. Box 1, folder 35. 1909-19. https://collections.library.yale.edu/catalog/11676600.

APA, 6th edition

Pratt, Richard Henry, 1840-1924. (["Box 1, folder 35"])(1909-19)[Bonnin, Gertrude S., 4 items]. https://collections.library.yale.edu/catalog/11676600.