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: 

Bibliographies & Literature Reviews

Encyclopedias, Handbooks, etc.