The following books must be read: edward carr's Twenty Years Crisis, Hans Morgenthau's Politics among Nations, Martin White's Power Politics, Kenneth Valts's Theory of International Politics, Nye and Keohan's Power and Interdependence, Keohan's After Hegemony and Winter's Social Theory of International Politics. Others can also look at robert jervis's Cognitive Logic in International Relations, Systematic Effect, Mearsheimer's Great Power Political Tragedy, Ruger's Multilateralism and so on.