Lunney, glynn, author
West, 2010
Buku Teks
Adelman, Martin J., author
Thomson/West, 2009
Buku Teks
Friedman, Robert D.
The Conservation Foundation, 1981
Buku Teks
Rubenstein, William, author
West A Tomson Reuters Busines, 2011
Buku Teks
by Alison Rieser ... [and others]
West Academic Publishing, 2013
Buku Teks