Friedman, Mark, author
Capstone Global Library, 2012
Buku Teks
McBeth, Adam, author
Oxford Univ Press, 2011
Buku Teks
United Nations , 1987
Buku Teks
Umar Ahmad Kasule, author
Noordeen, 2008
Buku Teks
Selby, David, author
Cambridge University Press, 1988
Buku Teks