Paul Fischer made me a vihuela in 1977 and we had to go to great lengths to find a suitable model, as there were not many extant from the period (the 1530s). We ended up using paintings and drawings of the time, and Paul produced an elegant instrument of sycamore, spruce and satinwood. It was much like the viola da mano, which was played by Francesco da Milano and that was actually my preferred repertoire at the time.
If this book had been available then, it would have been a useful guide to the accuracy of our guesses and also some of the personalities who were responsible for this forerunner of the modern guitar. Jose Romanillos, is of course, well known for his collaboration with Julian Bream, but is also a scholar of the history of guitar making and has written a book on Antonio Torres as well as this exhaustively researched volume.