Very Short Introductions to International Relations

The Very Short Introductions series (Harvard Login) from Oxford University Press offers concise introductions to a wide variety of topics, written by established scholars in that particular field. Because they are indeed very short, they are an excellent point of entry to a new field of study. The following Very Short Introductions are available in international relations and its subfields: 

International Relations: A Very Short Introduction, by Christian Reus-Smit (Harvard Login)
International Relations: A Very Short Introduction, by Paul Wilkerson (Harvard Login)
International Security: A Very Short Introduction (Harvard Login)
International Law: A Very Short Introduction (Harvard Login)
Globalization: A Very Short Introduction (Harvard Login)
Diplomacy: A Very Short Introduction (Harvard Login)
Peace: A Very Short Introduction (Harvard Login)
Modern War: A Very Short Introduction (Harvard Login)
Human Rights: A Very Short Introduction (Harvard Login)
The United Nations: A Very Short Introduction (Harvard Login)
Geopolitics: A Very Short Introduction (Harvard Login)
Borders: A Very Short Introduction (Harvard Login)
International Migration: A Very Short Introduction (Harvard Login)
Decolonization: A Very Short Introduction (Harvard Login)
American Foreign Relations: A Very Short Introduction (Harvard Login)

Bibliographies & Literature Reviews

Encyclopedias, Handbooks, etc.