Before visiting another library, it's always a good idea to check their catalog to make sure the material you want to see is available. You can generally find a library's catalog with a quick internet search. If you are planning to visit multiple external libraries or aren't quite sure where to go, merged library catalogues like Library Hub Discover and WorldCat can help you plan your research.
WorldCat is an international library catalogue. It is useful for looking for material on particular subjects and finding out in what libraries they are held. This makes it a very useful tool when you are planning a visit to another library.