The New Encyclopaedia Britannica : volume 25
Encyclopaedia Britannica Inc., 1988
 Buku Referensi
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
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The New Encyclopaedia Britannica : volume 25, micropaedia konowledge in depth
Encyclopaedia Britannica Inc., 2002
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The New Encyclopaedia Britannica : propaedia
Encyclopaedia Britannica Inc., 1988
 Buku Referensi