1. Article 54;M E Villiger;Commentary on the 1969 Vienna Convention on the Law of Treaties,2009
2. Article 54;T Giegerich;Vienna Convention on the Law of Treaties,2012
3. See also E. Osieke, Constitutional Law and Practice in the International Labour Organisation;E;Schermes and N.M. Blokker, International Institutional Law: Unity Within Diversity,1985