Chesters, Sarah Davey
Sense, 2012
eBooks
Chen, Liu-Fu
Philosophical Library, 1948
Buku Teks
Toynbee, Arnold J.
Oxford University Press, 1976
Buku Teks
George, Richard T. de
Regents Press of Kansas, 1980
Buku Referensi
Hepner, Harry W.
B.C. Forbes & Sons, 1953
Buku Teks