You may want to look at the AFE guides too - the physical size of the book is not as handy as Thom, but the content is good and has better illustrations on the whole. That said, if you plan to go beyond PPL, Thom is the more comprehensive manual as the AFE guides are mostly aimed at those not wishing to go beyond PPL. Personally, I still prefer a book to look at rather than trying to read a CDROM on a screen, but that's just me...