Robert M. Hutchins, Mortimer J. Adler, editors in chief
Encyclopaedia Britannica, Inc., 1963
Buku Referensi
Robert M. Hutchins, Mortimer J. Adler, editors in chief
Encyclopaedia Britannica, Inc., 1963
Buku Referensi
Wilson, Edmund, 1895-1972
Penguin Books, 1993
Buku Teks
Williams, Harold Herbert
Sidgwick & Jackson, 1918
Buku Teks
edited by Louis G. Locke, William M. Gibson, George Arms
Holt, Rinehart and Winston, 1959
Buku Teks