Do yourself a favor and buy the 3 books at once from Aircraft Spruce. My collection has vol 1 from AS, vol 2 and 3 from eBay. The eBay volumes were well worn and a bit dirty. I did not save that much but they were available immediately. These books are a good starting point for designing from scratch a Part 103 Trike Cart for my Paramotor. Strojnik is an excellent teacher. The books are east to read and the subject matter is not dumbed down.