MLA

Day, Jeremiah, 1773-1867. Letters. Box 1, folder 1-38. 1797-1863. https://collections.library.yale.edu/catalog/2067482.

APA, 6th edition

Day, Jeremiah, 1773-1867. (["Box 1, folder 1-38"])(1797-1863)[Letters]. https://collections.library.yale.edu/catalog/2067482.