Muzos, Steven J.
Harper Collins College, 1992
Buku Teks
Garfield, Paul J.
Prentice-Hall, 1964
Buku Teks
Wallace, Hugh A.
McGraw-Hill, 1967
Buku Teks
Richardson, John E.
Palgrave Macmillan, 2007
Buku Teks
Wallace, Harold R.
South-Western Educational, 1995
Buku Teks