Parker, Steve
Parragon, 2000
Buku Referensi
Fahnestock, James D.
Ziff Publishing, 1959
Buku Teks SO
Westcott, Charles G.
Howard W. Sams, 1964
Buku Teks
Dobson, Ann
grolier international, 1999
Buku Teks
Donald J. Griffin, editor
Jones & Bartlett Learning, 2011
Buku Teks