You can search the library catalog here:
Once you have found one or more books that are useful in the catalog, you may notice that they usually have "Subject Headings" attached to each record.
Subject Headings are agreed upon words and phrases to describe a topic (e.g. Foreign Relations), or idea/concept (e.g. Freedom), or a proper name or place (e.g. Obama, Barack; or France).
Each item record in the catalog may contain one or several assigned Subject Headings. When you've found useful items from another search, you can use the subject headings to find other, similarly tagged items.
Some examples:
Subject heading searches require exact matches, so it's usually easier to start with a keyword search and progress from there.
There are a large number of subject headings related to International Politics, including:
Dartmouth has arrangements with other libraries that let you request any items you can't find on campus. You can use BorrowDirect, which searches the catalogs of the Ivy Plus Libraries, or DartDoc, which lets you request items from anywhere.