MLA

Office, Oregon. Surveyor Generals. Map of Oregon Territory West of the Cascade Mountains / Surveyor General's Office. The Surveyor General, 0AD. https://collections.library.yale.edu/catalog/15821567.

APA, 6th edition

Office, O. S. G. (0 C.E.). Map of Oregon Territory west of the Cascade Mountains / Surveyor General's Office. [Maps]. The Surveyor General, https://collections.library.yale.edu/catalog/15821567.