MLA

Sanborn-Perris Map Co., issuing body. Insurance Maps of Willimantic, Windham Co., Conn. 1897. https://collections.library.yale.edu/catalog/11679622.

APA, 6th edition

Sanborn-Perris Map Co., issuing body. (1897). Insurance maps of Willimantic, Windham Co., Conn. [Atlases--Connecticut--Willimantic--1897, Cadastral maps--Connecticut--Willimantic--1897, Fire insurance maps--Connecticut--Willimantic--1897]. https://collections.library.yale.edu/catalog/11679622.