Good book for tube amps

[bolso103]

I am an electronic engineering advanced student, and I am looking for a good tube amp book. Last year I made a JTM45 replica, but I would like to acquire better acknowledge in biasing, i.e., which variable to measure over the oscilloscope and why.
I trust in technicians, but I do not want to spend money, when I am being engeneer in a year.

Thank you,
Gabriel

[axeman]

http://www.aikenamps.com/" onclick="window.open(this.href);return false;

[bolso103]

Thank you very much!