National highways map of the State of Pennsylvania : showing three thousand miles of national highways proposed by the National Highways association / John C. Mulford, cartographer.
MLA
Mulford, John C. National Highways Map of the State of Pennsylvania : Showing Three Thousand Miles of National Highways Proposed by the National Highways Association / John C. Mulford, Cartographer. National Highways Association, 1915. https://collections.library.yale.edu/catalog/15827676.
APA, 6th edition
Mulford, J. C. (1915). National highways map of the State of Pennsylvania : showing three thousand miles of national highways proposed by the National Highways association / John C. Mulford, cartographer. [Maps]. National Highways Association, https://collections.library.yale.edu/catalog/15827676.
