MLA

Edwards, Jonathan, 1703-1758. 5. 1757 Mar 24. JE. Fragment of a letter to Timothy Edwards. Also, transcript of the same letter, in an unidentified hand.. Box 7, folder 274. 1757 March 24. https://collections.library.yale.edu/catalog/33307473.

APA, 6th edition

Edwards, Jonathan, 1703-1758. (["Box 7, folder 274"])(1757 March 24)[5. 1757 Mar 24. JE. Fragment of a letter to Timothy Edwards. Also, transcript of the same letter, in an unidentified hand.]. https://collections.library.yale.edu/catalog/33307473.