The World book encyclopedia
World Book, 1992
 Buku Referensi
The World book encyclopedia : volume 1
World Book, 1985
 Buku Referensi
The World book encyclopedia : volume 2
World Book, 1985
 Buku Referensi
The World book encyclopedia : volume 3
World Book, 1985
 Buku Referensi
The World book encyclopedia : volume 4
World Book, 1985
 Buku Referensi