Telefunken Tube Information Sources?

Can those who are deep into vacuum tubes direct me to the best (The best Jerry, the best) sources of information on small signal Telefunken tubes, particularly the 12AX7 and 12AT7? I see them priced from reasonable to VERY expensive, and I don't even know the desirability of the ribbed vs. smooth plate versions. I gotta finally educate myself!
Here's the link to Brent Jesse's website , you can click on the tube variant you are interested in and he gives insights into the respective tube family as well as on the tube brands for that tube type, and availability. I am only a customer. Hope it helps
Great, thanks. I've seen Brent's name mentioned often as one of the couple of best sellers of vintage and rare tubes, glad he also provides knowledgeable info on them.
Here's a great link that covers all signal tubes. It's been around for quite awhile but has great info on tubes. I've used it for years and got alot of info. Its Joe's Tube Lore.
Alo do a search on the Asylum Tube section for posts from Bambi B. A lot of great firsthand use info on the 12AT7 variants.
@bdp24  Joe's tube lore is a good reference, but I would not call it accurate regarding 12AX7s. He makes no pretense saying he doesn't like this tube type. 

Brent Jessee has a better description of sonics on different brands and tube types.

One characteristic of Telefunken is they are extremely linear. So, no sweet mids, but great dynamics and open sonics.
 And it's true that Siemens rival Tely's. 

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Thanks one and all. @jab, I know what you mean, but I'll be okay ;-) . I have only a coupla AX and AT in my RIAA phono amp (a Herron), my line stage using a pair of 7JD8, which are cheap. I'm not necessarily going to buy Telefunkens, but I want to know about them in case I find some for cheap. I recently worked with a bassist who is also a ham operator, and he tells me he has a large stash of vintage tubes. I'm gonna go have a look!