source | https: //www.bethlehem-pa.gov/CityOfBethlehem/media/DCED-Media-Library/PlanningZoning/Historic_District_Mt_Airy_Map.pdf; https: //www.bethlehem-pa.gov/Community-Economic-Development/Planning-Zoning/Historic-and-conservation-Districts#: ~: text=Bethlehem%20Hist |