I have found the best on-line source for tube info in Frank's Electron Tube
Data sheets at
http://tubes.mkdw.net/index.html. For some reason, the USA
link is dead, but any of the other links will work, and they all have
identical data. I usually click on the Australian or German one. You can find data
on obscure tubes such as subminiatures, European types and special military
types. On most tube types there are multiple data sheets of data published
by different manufacturers, which sometimes gives you more information than
books like the RCA, GE or Eimac manuals.
The dead USA link could be a problem if you happen to have that one bookmarked.
