Rom, William N.
Jossey- Bass, 2012
Buku Teks
edited by Bhola R. Gurjar, Luisa T. Molina, Chandra S. P. Ojha ; foreword by Mario J. Molina
CRC Pres, 2010
Buku Teks
Wilner, Daniel M.
Macmillan, 1973
Buku Teks
Michael T. Haneline, William C. Meeker, editor
Jones and Bartlett Learning, 2011
Buku Teks
Davenport, S.J.
Washington, DC: United States Department of the Interior, 1954
Buku Teks