1. Mitchell, D.R.: Segregation in the Handling of Coal. American Institution of Mining, Metallurgical and Petroleum Engineers. Trans. 130 (1938)
2. Sherman, R.A, Kaiser, E.R: Segregation of Coal in an Industrial Steam Plant Bunker. Combustion, December 1937, pp. 25–28.
3. Holmes. Colliery Engr. (1934) 11.
4. Castanoli: Amer. Min. Congress Yearbook (1935), 270.
5. Hebley: Appalachian Coals, Inc., Fuel Engineers Meeting, July 1936.