Asher & Adams' Montana : eastern portion.
MLA
Asher & Adams' Montana : Eastern Portion. Asher & Adams, 1874. https://collections.library.yale.edu/catalog/15814907.
APA, 6th edition
Asher & Adams' Montana : eastern portion. (1874). [Maps]. Asher & Adams, https://collections.library.yale.edu/catalog/15814907.