MLA

Co, J. L. Smith. Map Showing Oregon & Washington Territory R.R. Co. J.L. Smith, 1888. https://collections.library.yale.edu/catalog/15821623.

APA, 6th edition

Co, J. L. S. (1888). Map showing Oregon & Washington Territory R.R. Co. [Maps]. J.L. Smith, https://collections.library.yale.edu/catalog/15821623.