Virtue's new treasury of knowledge : volume 4
Virtue, 1974
 Buku Referensi
Virtue's new treasury of knowledge : volume 3
Virtue, 1974
 Buku Referensi
Virtue's new treasury of knowledge : volume 2
Virtue, 1974
 Buku Referensi
Virtue's new treasury of knowledge : volume 5
Virtue, 1974
 Buku Referensi
Virtue's wonder world of knowledge : volume 1
Virtue & Company Limited, 1981
 Buku Referensi