Waldmann, Raymond J.
American Enterprise Institute , 1980
Buku Teks
Kline, John M., author
Quorum Books, 1985
Buku Teks
Ziegler, Raymond J.
Appleton-Century-Crofts, 1966
Buku Teks
Feld, Werner J., author
Pergamon Press, 1980
Buku Teks
Kohona, Palitha T.B., author
Martinus Nijhoff, 1985
Buku Teks