Cite

Pennsylvania-Maryland : Gettysburg battlefield and vicinity / U.S. Geological Survey.

MLA

Geological Survey (U.S.). Pennsylvania-Maryland : Gettysburg battlefield and vicinity / U.S. Geological Survey.. BRBL_00499. 1913. https://collections.library.yale.edu/catalog/15827668.

APA, 6th edition

Geological Survey (U.S.). (["BRBL_00499"])(1913)[Pennsylvania-Maryland : Gettysburg battlefield and vicinity / U.S. Geological Survey.]. https://collections.library.yale.edu/catalog/15827668.