The Erie Railway Report, The Railroad Gazette, Jan. 6, 1872; page 422. See final two paragraphs, column 2.
L. U. Reavis, St. Louis, Vandalia, Terre Haute, and Indianapolis R. R., The Railway and River Systems of St. Louis, Woodward, Tiernan and Hale, St. Louis, 1879; page 58.
No. 1737, Grafton T. Nutter, Jersey City, New Jersey., U.S., November 2, 1872, for 10 years: "A Railway Wagon Lifting Machine", The Canadian Patent Office Record, Vol. 1, No. 1 (March 1873); page 8.
"PRR Chronology, 1948"(PDF). The Pennsylvania Railroad Technical & Historical Society. September 2004. Archived from the original(PDF) on September 29, 2007.
"PRR Chronology, 1948"(PDF). The Pennsylvania Railroad Technical & Historical Society. September 2004. Archived from the original(PDF) on September 29, 2007.