The New Encyclopaedia Britannica : volume 6
Encyclopaedia Britannica Inc., 1978
 Buku Referensi
The New Encyclopaedia Britannica : volume 6
Encyclopaedia Britannica Inc., 1983
 Buku Referensi
The New Encyclopaedia Britannica : volume 6
Encyclopaedia Britannica Inc., 1988
 Buku Referensi
The New Encyclopaedia Britannica : volume 6, micropaedia ready reference
Encyclopaedia Britannica Inc., 2002
 Buku Referensi
The New Encyclopaedia Britannica : volume 6, micropaedia ready reference
Encyclopaedia Britannica Inc., 1998
 Buku Referensi