Schubert, Glendon
Scott, Foresman, 1965
Buku Teks
Unger, Roberto Mangabeira
Free Press, 1976
Buku Teks
Hartzler, H.Richard
Kennikat Press, 1976
Buku Teks SO
Carlston, Kenneth S.
Columbia University Press, 1956
Buku Teks SO
Hall, Jerome
Louisiana State University Press, 1963
Buku Klasik