I agree with Dazey. GS9 read through the first 2 like a novel. I spot checked his comprehension on the tests and let him go. In addition, we ordered directly from http://www.stanleyschmidt.com/FredGauss/index2.html and they came autographed! GS9 was tickled to death to have them autographed by the author! I didn't buy the whole series, but we will over the next year or so.