Kogel, Jessica Elzea (editor) (2006) Industrial minerals & rocks: commodities, markets, and uses (7th edition) Society for Mining, Metallurgy, and Exploration (U.S.), Littleton, Colorado, page 379, ISBN 0-87335-233-5.
worldcat.org
United States Bureau of Mines (1980) Selective Interburden Handling Techniques National Technical Information Service, Springfield, Virginia, OCLC 42983831
