MLA

Brush, George Jarvis, 1831-1912. Roepper, William Theodore (59). Box 4, folder 108. 1858-1867, 1869-1870, 1875, 1878-1879, undated. https://collections.library.yale.edu/catalog/32513522.

APA, 6th edition

Brush, George Jarvis, 1831-1912. (["Box 4, folder 108"])(1858-1867, 1869-1870, 1875, 1878-1879, undated)[Roepper, William Theodore (59)]. https://collections.library.yale.edu/catalog/32513522.