Macmillan Publishing Company, 1987
Buku Referensi
edited by Vergilius Ferm
Littlefield, Adam and Co., 1959
Buku Referensi
edited by Vergilius Ferm
Philosophical Library, 1945
Buku Referensi
edited by S. Flugge
Springer-Verlag, 1955
Buku Referensi
Toynbee, Arnold J., author
Oxford University Press, 1955
Buku Teks