Brown, Lester R., author
W.W.Norton, 1995
Buku Teks
WW Norton and Company, 2002
Buku Teks
Bashir, Sajitha, author
The World Bank, 2009
Buku Teks
edited by F. Lance Craigead, Charles L. Convis Jr
Esri Press, 2013
Buku Teks
edited by Corinne Mulley, John D. Nelson
Emerald, 2016
eBooks