MLA

Edwards, Jonathan, 1703-1758. 2. 1758 Mar 22. Shippen, William. Transcript of a letter to Mrs. Sarah Edwards, in the hand of Sereno E. Dwight.. Box 7, folder 290. 1758 March 22. https://collections.library.yale.edu/catalog/33307580.

APA, 6th edition

Edwards, Jonathan, 1703-1758. (["Box 7, folder 290"])(1758 March 22)[2. 1758 Mar 22. Shippen, William. Transcript of a letter to Mrs. Sarah Edwards, in the hand of Sereno E. Dwight.]. https://collections.library.yale.edu/catalog/33307580.