MLA

Engineering, Union, and Surveying Co. New Map, Washington, D.C. : Compiled from Official Surveys and Best Authorities. Union Engineering & Surveying Co. ;, Wm. A. Flamm, sales agent, 0AD. https://collections.library.yale.edu/catalog/15811209.

APA, 6th edition

Engineering, U., & Co, S. (0 C.E.). New map, Washington, D.C. : compiled from official surveys and best authorities. [Maps]. Union Engineering & Surveying Co. ;, Wm. A. Flamm, sales agent, https://collections.library.yale.edu/catalog/15811209.