MLA

Co, Great West Drafting. Map of the City of Calgary / Compiled from Registered Plans by the Great West Drafting Co. D.J. Young & Co., 0AD. https://collections.library.yale.edu/catalog/15536051.

APA, 6th edition

Co, G. W. D. (0 C.E.). Map of the city of Calgary / compiled from registered plans by the Great West Drafting Co. [Maps]. D.J. Young & Co., https://collections.library.yale.edu/catalog/15536051.