^Harding, J. W.. Firing of Locomotives, published by International Textbook Company, Scranton, PA, pp. 44-45, Table III Composition and Heating Values of Canadian Coals, part 1, copyrighted, part 1 1920, part 2 1912, part 3 1928.
^alegresoftware. "MetricMaster 4.3.0", definition of British thermal units (39.1°F), Pitt Meadows, BC, Canada, 1989-2004. Retrieved May 23, 2007.