Eckes, George, author
McGraw-Hill, 2005
Buku Teks
Gates, Bill, author
John Wiley, 1998
Buku Teks
Trautman, Neal E., author
Charles C Thomas Publisher, 1990
Buku Teks
Crainer, Stuart
Capstone, 1998
Buku Teks
Windrow, Martin, author
Grange Books, 2000
Buku Referensi