Davenport, S.J.
Washington, DC: United States Department of the Interior, 1954
Buku Teks
Colbeck, I. (Ian)
Elsevier, 1994
Buku Teks
De Nevers, Noel, 1932-
McGraw-Hill, 2000
Buku Teks
Paul L. Magill, Francis R. Holden, Charles Ackley, editor; Frederick G. Sawyer, editorial consultant
McGraw-Hill, 1956
Buku Referensi
Pepper, Darrell W.
Imperial College Press, 2009
Buku Teks