MLA

G. W., et al. Colton's New Township Map of the State of Connecticut / G.W. & C.B. Colton & Co. G.W. & C.B. Colton & Co., 1879. https://collections.library.yale.edu/catalog/15654737.

APA, 6th edition

G. W., Colton, C. B., & C. (1879). Colton's new township map of the state of Connecticut / G.W. & C.B. Colton & Co. [Maps]. G.W. & C.B. Colton & Co., https://collections.library.yale.edu/catalog/15654737.