Cite

The official Montana 1977 highway map / prepared by the H.M. Gousha Company.

MLA

Company, H. M. Gousha. The Official Montana 1977 Highway Map / Prepared by the H.M. Gousha Company. State Highway Commission, 0AD. https://collections.library.yale.edu/catalog/15818320.

APA, 6th edition

Company, H. M. G. (0 C.E.). The official Montana 1977 highway map / prepared by the H.M. Gousha Company. [Road maps]. State Highway Commission, https://collections.library.yale.edu/catalog/15818320.