Natural law

A Discourse on the Study of the Law of Nature and Nations

James Sir Mackintosh

The Declaration of the Rights of Man and of Citizens

Georg Jellinek

Tradition, Principally with Reference to Mythology and the Law of Nations

John Francis Arundell Baron Arundell of Wardour

The Rights of War and Peace

Hugo Grotius

A Discourse Upon the Origin and the Foundation of the Inequality Among Mankind

Jean-Jacques Rousseau