Cite

South Dakota highways / prepared by the South Dakota State-wide Highway Planning Survey ; drawn by Ralph S. O'Neill, 1939.

MLA

O'Neill, Ralph S. South Dakota Highways / Prepared by the South Dakota State-Wide Highway Planning Survey ; Drawn by Ralph S. O'Neill, 1939. South Dakota State Highway Commission, 0AD. https://collections.library.yale.edu/catalog/15814764.

APA, 6th edition

O'Neill, R. S. (0 C.E.). South Dakota highways / prepared by the South Dakota State-wide Highway Planning Survey ; drawn by Ralph S. O'Neill, 1939. [Road maps]. South Dakota State Highway Commission, https://collections.library.yale.edu/catalog/15814764.