MLA

Johnson, Guy, approximately 1740-1788. Dorchester, Guy Carleton to GJ. Box 1, folder 16. 1775 Jun 19. https://collections.library.yale.edu/catalog/17280541.

APA, 6th edition

Johnson, Guy, approximately 1740-1788. (["Box 1, folder 16"])(1775 Jun 19)[Dorchester, Guy Carleton to GJ]. https://collections.library.yale.edu/catalog/17280541.