MLA

Powers, Mary Rockwood, d. 1858. The overland route, leaves from the journal of a California emigrant /by Mary L. Rockwood Powers, 1859. 1859. https://collections.library.yale.edu/catalog/9998665.

APA, 6th edition

Powers, Mary Rockwood, d. 1858. (1859)[The overland route, leaves from the journal of a California emigrant /by Mary L. Rockwood Powers, 1859]. https://collections.library.yale.edu/catalog/9998665.