edited by Mortimer J. Adler
Encyclopedia Britanica, 1990
Buku Referensi
Andi Achdian, author
Kekal presss, 2011
Buku Teks
Valentia, Erich
Gemenschaff, 1957
Buku Teks
Zulhasril Nasir, author
Ombak, 2007
Buku Teks
Southall, Ivan, author
Melbourne: Oxford University Press, 1964
Buku Teks