Williamson, Samuel J.
Addison-Wesley, 1973
Buku Teks
Davenport, S.J.
Washington, DC: United States Department of the Interior, 1954
Buku Teks
Colbeck, I. (Ian), author
Elsevier, 1994
Buku Teks
De Nevers, Noel, 1932-, author
McGraw-Hill, 2000
Buku Teks
Paul L. Magill, Francis R. Holden, Charles Ackley, editor; Frederick G. Sawyer, editorial consultant
McGraw-Hill, 1956
Buku Referensi