MLA

Sanborn Map Company, issuing body. Insurance Maps of Westport, Fairfield County, Connecticut. 1940. https://collections.library.yale.edu/catalog/11676591.

APA, 6th edition

Sanborn Map Company, issuing body. (1940). Insurance maps of Westport, Fairfield County, Connecticut. [Atlases--Connecticut--Greens Farms--1940, Atlases--Connecticut--Saugatuck--1940, Atlases--Connecticut--Westport--1940, Cadastral maps--Connecticut--Greens Farms--1940, Cadastral maps--Connecticut--Saugatuck--1940, Cadastral maps--Connecticut--Westport--1940, Fire insurance maps--Connecticut--Greens Farms--1940, Fire insurance maps--Connecticut--Saugatuck--1940, Fire insurance maps--Connecticut--Westport--1940]. https://collections.library.yale.edu/catalog/11676591.