MLA

Brush, George Jarvis, 1831-1912. Farnum, William W. (4). Box 2, folder 47. 1899-1900. https://collections.library.yale.edu/catalog/32512867.

APA, 6th edition

Brush, George Jarvis, 1831-1912. (["Box 2, folder 47"])(1899-1900)[Farnum, William W. (4)]. https://collections.library.yale.edu/catalog/32512867.