MLA

Sanborn Map Company, issuing body. Insurance Maps of Greenwich, Connecticut. 1920. https://collections.library.yale.edu/catalog/11128864.

APA, 6th edition

Sanborn Map Company, issuing body. (1920). Insurance Maps of Greenwich, Connecticut. [Atlases--Connecticut--Greenwich (Town)--1920.--local, Cadastral maps--Connecticut--Greenwich (Town)--1920.--local]. https://collections.library.yale.edu/catalog/11128864.