Wagner, Scott A., author
CRC Press, Taylor & Francis Group, 2009
Buku Teks
USAID, 2003
Buku Teks
Clark, William S., author
Houghton-Miffiln, 1987
Buku Teks
Nelson, Stephen L., author
Elex Media Komputindo, 1997
Buku Teks
Angier, Bradford, author
Stackpole Books, 1992
Buku Teks