Neumann, Richard K.
Wolters Kluwer Law & Business, 2013
Buku Teks SO
Brown, Gordon W.
Prentice-Hall, 1990
Buku Referensi
Friedmann, Wolfgang, 1907-1972
Stevens & Sons, 1949
Buku Teks
Guandola, M.H.
Merriam & Webster, INC, 1989
Buku Teks
Friedmann, Wolfgang, 1907-1972
Columbia University Press, 1967
Buku Teks