Hi All, 

For those of you on a limited budget & can't afford to run out & spend some monies on expensive books...the local library may be a help to you. If your local library has WorldCat access and participates in interlibrary loans...here's some titles I found and their WorldCat numbers...they were delivered to my university library within a week: 

The Tube Amp Book, R. Aspen Pittman (7061292) 
Inside Tube Amps, Torres (7061429) 
Great Tube Amp & Guitar Mods, Thompson (7061363) 
The Ultimate Tone, O'Connor (7061544) 
Tonnes of Tone, O'Connor (7061487) 

At least this way you can check them out before you buy them. I was able to get them for about 3 weeks which seems to be more than enough time to browse through & learn a bit. 

BradM