edited by Dagobert D. Runes
Littlefield, Adams & Co., 1959
Buku Referensi
Thomas, Henry, author
Blakiston, 1946
Buku Teks
Christensen, Kit R., author
McGraw-Hill, 2002
Buku Teks
edited by F.S.C. Northrop
Yale University Press, 1949
Buku Teks
Reader in Philosophy, University of The Panjab, 1965
Buku Teks