^
Monroe, James Stewart; Wicander, Reed; Hazlett, Richard W. (2007). "4". In Dodson, Keith (ed.). Physical Geology: Exploring the Earth. Earth Sciences (6 ed.). USA: Thompson Brooks/Cole. p. 115. ISBN 0495011487.
^
Blatt, Harvey; Tracy, Robert J. (1996). Petrology : igneous, sedimentary, and metamorphic (2nd ed.). New York: W.H. Freeman. pp. 12–13. ISBN 0716724383.