Gregor, A. James
Ethics and Public Policy Center, 1984
Buku Teks
Timberman, David G.
M.E. Sharpe, 1991
Buku Teks
Smit, C.
Wolters-Noordhoff, 1970
Buku Teks
Smith, Jean Edward
Simon & Schuster,, 2016
Buku Teks
Ramos, Fidel V.
Friends of Steady Eddie , 1992
Buku Teks