MLA

Whitney, W. H. Whitney's Map of Port Townsend and Environs, Washington : Compiled from Official Records. Miller & Going, civil engineers, 1890. https://collections.library.yale.edu/catalog/15821651.

APA, 6th edition

Whitney, W. H. (1890). Whitney's map of Port Townsend and environs, Washington : compiled from official records. [Maps]. Miller & Going, civil engineers, https://collections.library.yale.edu/catalog/15821651.