Collier's encyclopedia : volume 2
Macmillan Educational Company, 1990
 Buku Referensi
Collier's encyclopedia, with bibliography and index : volume 1
P.F. Collier & Son, 1954
 Buku Referensi
Collier's encyclopedia, with bibliography and index : volume 3
P.F. Collier & Son, 1954
 Buku Referensi
Collier's encyclopedia, with bibliography and index : volume 4
P.F. Collier & Son, 1954
 Buku Referensi
Collier's encyclopedia, with bibliography and index : volume 5
P.F. Collier & Son, 1954
 Buku Referensi