Kornblum, William, author
Prentice-Hall, 1992
Buku Teks
Scarpitti, Frank R., author
Holt, Rinehart and Winston, 1974
Buku Teks
Palen, J. John, author
McGraw-Hill, 1979
Buku Teks
Cohen, Nathan Edward, author
National Ass. of Workker, 1964
Buku Teks
Kelsen, Hans, author
Clarendon Press Oxford, 1992
Buku Teks