Davenport, S.J.
Washington, DC: United States Department of the Interior, 1954
Buku Teks
De Nevers, Noel, 1932-
McGraw-Hill, 1995
Buku Teks
Colbeck, I. (Ian)
Elsevier, 1994
Buku Teks
Devinny, Joseph S.
Lewis Publishers, 1999
Buku Teks
Heihnson, Robert Jennings
Prentice-Hall, 1999
Buku Teks