I agree with k3n that the book(s) are particularly valuable when you're making a OBW for the first time. I continue to refer to mine, even after making several. Many questions that are asked here are answered in the book, including examples of how to select fabric for the OBW, what works and what doesn't, how much fabric to get, how to line up the layers, how to press, etc. I thought the instructions were excellent, and the pictures of finished quilts were inspirational - lots of ideas on how to finish the quilt with borders, cubes, etc. I only have the first book, so can't speak for the others.