Taliaferro, Charles
Blackwell, 1998
Buku Teks SO
Pojman, Louis P.
Cengage Learning, 2012
Buku Teks SO
Ajarananda, Swami
Thai Bidhaya Press, [date of publication not identified]
Buku Klasik
Dampier, William Cecil
Cambridge University Press, 1989
Buku Teks SO
Herman, A.L.
Westview Press, 1991
Buku Referensi