MLA

Cooper, James Fenimore, 1789-1851. Wilkes, Charles. Box 9, folder 266. 1823-1850. https://collections.library.yale.edu/catalog/16723326.

APA, 6th edition

Cooper, James Fenimore, 1789-1851. (["Box 9, folder 266"])(1823-1850)[Wilkes, Charles]. https://collections.library.yale.edu/catalog/16723326.