MLA

Audubon, John James, 1785-1851. Morris, John Brande to JJA. Box 5, folder 253. 1836 Sep 19. https://collections.library.yale.edu/catalog/16445230.

APA, 6th edition

Audubon, John James, 1785-1851. (["Box 5, folder 253"])(1836 Sep 19)[Morris, John Brande to JJA]. https://collections.library.yale.edu/catalog/16445230.