MLA

Whitman, Walt, 1819-1892. Bastide, Charles. Box 1, folder 10. 1906 Nov 15. https://collections.library.yale.edu/catalog/2053644.

APA, 6th edition

Whitman, Walt, 1819-1892. (["Box 1, folder 10"])(1906 Nov 15)[Bastide, Charles]. https://collections.library.yale.edu/catalog/2053644.