Travers, Kenneth J.
Laidlaw Brothers, 1987
Buku Teks
Jurgensen, Ray C.
Houghton-Miffiln, 1983
Buku Teks
Brumfiel, Charles Francis, 1914-
Addison-Wesley, 1962
Buku Teks
Gibilisco, Stan, 1953-
McGraw-Hill, 2011
Buku Teks
Hill, G.A.
Ginn, 1889
Buku Teks SO