Chicago, Encyclopedia Britanica, Inc,, 1996
Buku Referensi
Adler, Mortimer J.,, editor in chief
Chicago, Encyclopedia Britanica, Inc, , 1995
Buku Referensi
Adler, Mortimer J., editor in chief
Chicago, Encyclopedia Britanica, Inc, 1990, 1994
Buku Referensi
Mortimer J. Adler, editor in chief ; Clifton Fadiman, Philip W. Goetz, associate editors
Encyclopedia Britanica, 1990
Buku Referensi
editor in chief, Mortimer J. Adler
Encyclopedia Britanica, 1996
Buku Referensi