Free e-book.  Written by world renowned veterinary behaviorist and trianer Dr Ian Dunbar, this book is an excellent resource!  While it says "puppy" in the title, the information in this book also applies to adult dogs.  You will learn what to think about before getting your dog and also what to expect after getting your dog, whether it be a puppy or adult dog.
 
This free e-book is available to anyone in any country.