La Pennsylvanie et ses exploitations variées. - International congress of navigation. 1912. Philadelphia; Whidden, Guy C. (Guy Carleton), 1868-; Schoff, Wilfred H. (Wilfred Harvey), 1874-1932. ([Philadelphia : Printed by the Beck engraving company, 1912)
Keywords: Pennsylvania -- Economic conditions; Industries -- Pennsylvania; Transportation -- Pennsylvania; Education -- Pennsylvania