MLA

Sanborn Map Company, issuing body. Watertown, Litchfield County, Conn. 1927. https://collections.library.yale.edu/catalog/11676459.

APA, 6th edition

Sanborn Map Company, issuing body. (1927). Watertown, Litchfield County, Conn. [Atlases--Connecticut--Watertown--1927, Cadastral maps--Connecticut--Watertown--1927, Fire insurance maps--Connecticut--Watertown--1927]. https://collections.library.yale.edu/catalog/11676459.