MLA

Emory, William H. (William Hemsley), 1811-1887. Correspondence. Box 4, folder 22. 1849 Dec. https://collections.library.yale.edu/catalog/16686611.

APA, 6th edition

Emory, William H. (William Hemsley), 1811-1887. (["Box 4, folder 22"])(1849 Dec)[Correspondence]. https://collections.library.yale.edu/catalog/16686611.