Map of Maryland showing state road system and state aid roads : completed or under construction December 31, 1911.
MLA
Map of Maryland Showing State Road System and State Aid Roads : Completed or under Construction December 31, 1911. Maryland Geological Survey, 1910. https://collections.library.yale.edu/catalog/15827477.
APA, 6th edition
Map of Maryland showing state road system and state aid roads : completed or under construction December 31, 1911. (1910). [Maps]. Maryland Geological Survey, https://collections.library.yale.edu/catalog/15827477.