The only comprehensive book length study of the book test that I know of, and the fact that it was written over 50 years ago and still contains untapped ideas in this area (as well as completely prefiguring numerous 'new' methods that have received commercial release in the intervening years) is a testament to the depth of Boarde's scholarship and the quality of his thinking. Many, many brilliant methods , and after reading this much of the current crop will appear slightly less novel...