"University of Pittsburgh. University Library System. Digital Research Library." . . . . . . . . "Introduction to a history of ironmaking and coal mining in Pennsylvania. : Contributed to the final report of the Pennsylvania Board of Centennial Managers"@en . . . . . "Introduction to a history of ironmaking and coal mining in Pennsylvania Contributed to the final report of the Pennsylvania Board of Centennial Managers"@en . . . "Introduction to a history of ironmaking and coal mining in Pennsylvania" . . "Introduction to a history of ironmaking and coal mining in Pennsylvania"@en . . . "Introduction to a history of ironmaking and coal mining in Pennsylvania : Contributed to the final report of the Pennsylvania Board of centennial managers"@en . . . . . . "Introduction to a history of ironmaking and coal mining in pennsylvania"@en . . "Introduction to a history of ironmaking and coal mining in Pennsylvania : contributed to the final report of the Pennsylvania Board of centennial managers"@en . "History"@en . . . "Introduction to a history of ironmaking and coal mining in Pennsylvania : contributed to the final report of the Pennsylvania Board of Centennial Managers"@en .