Hart, 2008
Buku Teks
Cambridge University Press, 2018
eBooks
Bonanomi, Elisabeth Burgi, author
Edward Elgar Publishing, 2015
Buku Teks
Qureshi, Asif H. , author
Sweet & Maxwell/Thomson Reuters, 2011
Buku Teks
United Nations
United Nations, 2002
Buku Teks