MLA

Downie, William, 1819-1893. Diary. Box 1, folder a. [1858?] Jan-Sep. https://collections.library.yale.edu/catalog/17440589.

APA, 6th edition

Downie, William, 1819-1893. (["Box 1, folder a"])([1858?] Jan-Sep)[Diary]. https://collections.library.yale.edu/catalog/17440589.