Jackson, Jennifer
Blackwell Publishers, 1996
Buku Teks
Desjardins, Joseph, author
McGraw-Hill, 2003
Buku Teks
Staley, Eugene, author
McGraw-hill, 1965
Buku Teks
Guelzo, Carl M.
Prentica-Hall , 1986
Buku Teks
Edey, Harold C.
Hutchinson's University Library , 1972
Buku Teks