One of the best books for classical (or to be more precise Baroque and Renaissance) music on the ukulele is in my opinion 'From Lute to Uke' by Tony Mizen. It was also one of the first to address this area, although it did come some time after John Kings 'Classical Ukulele'. In this video I go through what I like about the book and why it is so important. also play a couple of pieces from the book.