32. Degan, V. D., (1997), Sources of International Law, Netherlands, Kluwer Law.
33. Klabbers, Jan, (1998), the Concept of Treaty in International Law, Netherlands, Kluwer Law.
34. Fitzmaurice, M & Elias, O., (2005), Contemporary Issues in the Law of Treaties, Netherlands: Eleven International Publishing.
35. Vielleville, Daniel E., (2008), Sovereignty over Natural Resources Versus Rights Under Investment Contracts: Which One Prevails?" access on www.transnational-dispute-management.com
