The New Encyclopaedia Britannica : volume 26
Encyclopaedia Britannica Inc., 2003
 Buku Referensi
The New encyclopaedia Britannica : volume 26, macropaedia knowledge in depth
Encyclopaedia Britannica Inc., 1998
 Buku Referensi
The New Encyclopaedia Britannica : volume 26, micropaedia konowledge in depth
Encyclopaedia Britannica Inc., 2002
 Buku Referensi
Encyclopaedia universalis : volume 26
Encyclopaedia Universalis France S.A. , 1989
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The New Encyclopaedia Britannica : propaedia
Encyclopaedia Britannica Inc., 1988
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