Graham, Walter W.
Littlefield, Adams & Co., 1965
Buku Teks
Coaldrake, William Howard
Routledge, 1996
Buku Teks
Davidson, Peter
Academic Group, 1997
Buku Teks
Travers, Kenneth J.
Laidlaw Brothers, 1987
Buku Teks
Jurgensen, Ray C.
Houghton-Miffiln, 1983
Buku Teks