Smart, Terry L., author
Holt, Reinhart and Winston, 1987
Buku Teks
London Chancellor Press 1999,
Buku Referensi
Dorling Kindersley, 1998
Multimedia
Joseph Reither, editor
The New Home Library, 1942
Buku Teks
Evans, Jessie Campbell, author
D.C. Heath, 1942
Buku Teks