Pelletier, Kenneth R.
A Fireside Book, 2002
Buku Teks
Drury, Nevill
Hale & Iremonger , 1983
Buku Teks
Shealy, C. Norman
Element, 1998
Buku Referensi
Labriola, Dan
A Division of Prima Publishing, 2000
Buku Teks
Independence Educational , 1994
Buku Teks