Levi, Werner
Westview Press, 1991
Buku Teks
Klabbers, Jan, author
Cambridge University Press, 2002
Buku Teks
Starke, J.G., author
Butterworth , 1958
Buku Teks
Starke, J.G., author
Butterworth, 1977
Buku Teks
Klabbers, Jan, author
Cambridge University Press, 2009
Buku Teks