State Highway Department's map of the state of Oregon showing main traveled automobile roads / compiled and published by the Oregon State Highway Commission.
MLA
Commission, Oregon State Highway. State Highway Department's Map of the State of Oregon Showing Main Traveled Automobile Roads / Compiled and Published by the Oregon State Highway Commission. Oregon State Highway Commission, 1935. https://collections.library.yale.edu/catalog/15821617.
APA, 6th edition
Commission, O. S. H. (1935). State Highway Department's map of the state of Oregon showing main traveled automobile roads / compiled and published by the Oregon State Highway Commission. [Road maps]. Oregon State Highway Commission, https://collections.library.yale.edu/catalog/15821617.