Samuel Thomas (September 1899). "Reminiscences of the early anthracite-iron industry". Transactions of the American Institute of Mining Engineers (reprint by TheHopkinThomasProject.com). Archived from the original on 14 March 2014. Retrieved 5 December 2016.
Samuel Thomas (September 1899). "Reminiscences of the early anthracite-iron industry". Transactions of the American Institute of Mining Engineers (reprint by TheHopkinThomasProject.com). Archived from the original on 14 March 2014. Retrieved 5 December 2016.