Railroad Distance Map of the United States, Mexico, and Canada.
MLA
Railroad Distance Map of the United States, Mexico, and Canada. Warren Ayers, 0AD. https://collections.library.yale.edu/catalog/15827804.
APA, 6th edition
Railroad Distance Map of the United States, Mexico, and Canada. (0 C.E.). [Maps]. Warren Ayers, https://collections.library.yale.edu/catalog/15827804.