Carmody, Emmett J.
Oklahoma: CAD Press, c1989
Buku Teks
Traister, John E.
Reston Publishing , 1979
Buku Teks
Bethune, James D., author
Prentice-Hall, 1980
Buku Teks
Dickerson, Reed, author
Little, Brown and Company, 1954
Buku Teks
Snow, Charles W.
Prentice-Hall, 1976
Buku Teks