Harper, 1961
Buku Teks
Kansas City : University of Missouri
Majalah, Jurnal, Buletin
Ruggiero, Vincent Ryan, author
Alfred Publishing Co., Inc., 1981
Buku Teks
Ehrenhaft, George
Prima Publishing, 1999
Buku Teks
Lewis, Herschell Gordon, author
Prentice-Hall, 1988
Buku Teks