Amending the UN Charter, possibly through a Charter Review Conference under Article 109 of the UN Charter, is a commonly cited possibility. This is difficult because it requires ratification by two-thirds of UN members, including all five permanent members of the Security Council. There have been only five amendments to the UN Charter since 1945, and none of them were done through the Article 109 process. Louis Sohn and Grenville Clark, in their 1958 book "World Peace Through World Law", proposed establishing a UN Parliamentary Assembly through this method.