MLA

Emory, William H. (William Hemsley), 1811-1887. Correspondence. Box 4, folder 21. 1849 Nov. https://collections.library.yale.edu/catalog/16686610.

APA, 6th edition

Emory, William H. (William Hemsley), 1811-1887. (["Box 4, folder 21"])(1849 Nov)[Correspondence]. https://collections.library.yale.edu/catalog/16686610.