This book gives great coverage to a much lacking topic - the physical construction and testing of tube amplifiers (or, for that matter, any tube gear). It is the best work I have seen in this area, and is invaluable if you need it or are just interested in tube gear wiring and construction.
Tube circuitry is tangential to the information in the book, but it is not the main course here. There are many other books available that discuss tube amplifier circuits. There are few if any others that provide proper coverage of mechanical construction.