Official road map, Iowa / [prepared for] Conoco Travel Bureau.
MLA
Company, H. M. Gousha. Official Road Map, Iowa / [Prepared for] Conoco Travel Bureau. H.M. Gousha Company, 1937. https://collections.library.yale.edu/catalog/15814636.
APA, 6th edition
Company, H. M. G. (1937). Official road map, Iowa / [prepared for] Conoco Travel Bureau. [Road maps]. H.M. Gousha Company, https://collections.library.yale.edu/catalog/15814636.