Wicks, Rollo E.
N.Y. State Univ. of New York , 1958
Buku Teks SO
Tyabji, Husain B
Bombay Thacker & Co 1952
Buku Teks
Kuruvilla Pandikattu
Council for Research in Values and Philosophy, 2001
Buku Teks SO
Publication Division, 1884
Buku Referensi
Publication Division, 1883
Buku Referensi