Holmes, Richard, author
Harper Collins , 2001
Buku Teks
Willcox, William B., author
D.C. Heath and Company, 1988
Buku Referensi
Cannadine, David
Papermac, 1996
Buku Teks SO
Ekirch, A. Roger
Cloarendon Press, 1987
Buku Teks
Briggs, Asa
Longman, 1974
Buku Teks