The New Encyclopaedia Britannica : volume 13
Encyclopaedia Britannica Inc., 1978
 Buku Referensi
The New Encyclopaedia Britannica : volume 13
Encyclopaedia Britannica Inc., 1988
 Buku Referensi
The New Encyclopaedia Britannica : volume 13, micropaedia konowledge in depth
Encyclopaedia Britannica Inc., 2002
 Buku Referensi
The New Encyclopaedia Britannica : volume 13, macropaedia knowledge in depth
Encyclopaedia Britannica Inc., 1998
 Buku Referensi
Encyclopaedia Britannica : volume 13
Encyclopaedia Britannica Inc., 1967
 Buku Referensi