MLA

Welsh, Herbert, 1851-1941. Welsh, Herbert. Box 1 | Folder 42. 1893 February 9. https://collections.library.yale.edu/catalog/17157760.

APA, 6th edition

Welsh, Herbert, 1851-1941. (["Box 1 | Folder 42"])(1893 February 9)[Welsh, Herbert]. https://collections.library.yale.edu/catalog/17157760.