Bryson, Bill, author
Penguin Books, 1987
Buku Referensi
Saussy, George Stone, author
Penguin Books, 1986
Buku Referensi
LeMay, Harold, author
Facts on File, 1988
Buku Referensi
edited by Frank O. Colby
Thomas Y. Crowell, 1950
Buku Referensi
Tulloch, Sara
Oxford University Press, 1991
Buku Teks