MLA

Hale, Sarah Josepha Buell, 1788-1879. Letter : Philadelphia, to [John Denison Baldwin]. Box 34, folder GROUP 556, F-1. 1847 May 4. https://collections.library.yale.edu/catalog/17432534.

APA, 6th edition

Hale, Sarah Josepha Buell, 1788-1879. (["Box 34, folder GROUP 556, F-1"])(1847 May 4)[Letter : Philadelphia, to [John Denison Baldwin]]. https://collections.library.yale.edu/catalog/17432534.