The New Encyclopaedia Britannica : volume 25
Encyclopaedia Britannica Inc., 2003
 Buku Referensi
The New encyclopaedia Britannica : volume 25, macropaedia knowledge in depth
Encyclopaedia Britannica Inc., 1998
 Buku Referensi
The New Encyclopaedia Britannica : volume 25, micropaedia konowledge in depth
Encyclopaedia Britannica Inc., 2002
 Buku Referensi
Encyclopaedia universalis : volume 25
Encyclopaedia Universalis France S.A. , 1989
 Buku Referensi
The New Encyclopaedia Britannica : propaedia
Encyclopaedia Britannica Inc., 1988
 Buku Referensi