MLA

Sanborn Map Company, issuing body. New Milford, Litchfield County, Connecticut. 1931. https://collections.library.yale.edu/catalog/16055582.

APA, 6th edition

Sanborn Map Company, issuing body. (1931). New Milford, Litchfield County, Connecticut. [Atlases--Connecticut--New Milford--1931, Cadastral maps--Connecticut--New Milford--1931, Fire insurance maps--Connecticut--New Milford--1931]. https://collections.library.yale.edu/catalog/16055582.