Giordan, Giuseppe, editor
Springer, 2011
eBooks
Pojman, Louis P.
Cengage Learning, 2012
Buku Teks SO
Taliaferro, Charles
Blackwell , 1998
Buku Teks
edited by Andrew Eshleman
Blackwell, 2008
Buku Teks
Ajarananda, Swami
Thai Bidhaya Press, [date of publication not identified]
Buku Klasik