The World book encyclopedia : volume 18
World Book, 1984
Buku Referensi
The New Encyclopaedia Britannica : volume 18
Encyclopaedia Britannica Inc., 1988
Buku Referensi
The New Encyclopaedia Britannica : volume 18
Encyclopaedia Britannica Inc., 2003
Buku Referensi
The New Encyclopaedia Britannica : volume 18
Encyclopaedia Britannica Inc., 1978
Buku Referensi
The New Encyclopedia Britannica : volume 18
Encyclopedia Britannica, 1983
Buku Referensi