Would you like to have access to one “card catalog” that lets you search libraries from all over the world? You can do just that at WorldCat (http://www.worldcat.org). This site not only lets you search, but when you find an interesting book, it will list the closest libraries having a copy.
That’s pretty amazing, but that’s not all. If there’s a digital copy of the book, WorldCat will let you know. Need a citation for a book? WorldCat does that too – in a number of different formats. And, if you create a free account, you have even more functionality, like building your own lists of useful reference books.
There are also free mobile apps available for iOS and Android devices so you can take WorldCat with you.