This site functions more as a directory than an actual retailer. Let's you search 13,000 booksellers at one time.
Online retailer of both new and used books. Canadian users should use this link for Amazon.
Barnes & Noble
Online retailer of both new and used books.
Online retailer of new books.
Another retailer for our Canadian users.
Online retailer of dog books and products.
Publisher and online retailer of dog related books.
Buy and sell previously owned books.
Karen is a clicker trainer and offers books on her website.
Powell's City of Books
Online independent retailer of new and used books.
Online retailer of dog products, including books.
If you have any other suggestions on where to purchase books, please feel free to post below and I will add them to this list.