Petersen, Niels Max Planck Institute for Research on Collective Goods, Max Planck Society;
http://www.wcl.american.edu/journal/ilr/23/documents/PETERSENFINAL.pdf (beliebiger Volltext)
Petersen, N. (2008). Customary Law without Custom? Rules, Principles and the Role of State Practice in International Norm Creation. American University International Law Review, 275-310.