Is there a reference book for tube substitutions??

I have owned tube audio equipment for some time now, but have just started to get into the tube rolling game (funny thing; I have always experimented with NOS in my guitar amps but never my stereo). I am wondering if anyone knows of a good (but not too technical) reference book on tubes. I would love to find something that covers tube substitutions, history, and some technical background.


The Tube Substitution Book ,you can find it with a google search or go to ,dont know how complete it is ,,just came to mind !Ray
Several resources on the net just google, try also. I have a program that is called Duncans Amp Tools TDSL version 1 it was a free program from his website that crossrefrences tubes from various sources including schematics. Very cool.
Try this.

Tube Data Sheet Locator
I got my tube substitution book from Radio Shack years ago but it is no longer available. Parts Express sells a tube substitution handbook:
Thanks for the info all..... Nutella, great website. I am going to check the Parts Express book out as well.