MLA

Company, H. M. Gousha. Street Map of Portland / Copyright by the H.M. Gousha Company [for] Shell [Oil Company]. The H.M. Gousha Co., 0AD. https://collections.library.yale.edu/catalog/15821594.

APA, 6th edition

Company, H. M. G. (0 C.E.). Street map of Portland / copyright by the H.M. Gousha Company [for] Shell [Oil Company]. [Maps]. The H.M. Gousha Co., https://collections.library.yale.edu/catalog/15821594.