Sansom, George Bailey, Sir, 1883-1965
The Creasst Press, 1950
Buku Teks
Houghton Miffiln, 1954
Buku Teks
Johnson, Elmer D.
The Scarecrow Press, 1970
Buku Teks
editor in chief, Mortimer J. Adler
Encyclopedia Britanica, 1990
Buku Referensi
editor in cheief, Mortimer J. Adler
Encyclopedia Britanica, 1996
Buku Referensi