Quincy No. 2 Mine Hoist (1920) Archived 2011-07-17 at the Wayback Machine National Historic Engineering Landmark brochure, The American Society of Mechanical Engineers, 1984. http://files.asme.org/ASMEORG/Communities/History/Landmarks/5631.pdf
H.K. Burch and M.A. Witting, Automatic Operation of Mine Hoists, in Trans. Amer. Inst. of Mining Engineers, Vol. LV, 1016, page 10. https://books.google.com/books?id=oioLAAAAYAAJ
A.R. Lilly, Hoist Controller, U.S. Patent 3,110,199 granted Aug. 30, 1960.