Dutch company selling vacuum tubes online. Offering a stock audio valves and other kind of valves for amateur radio use.
http://www.rsc-valves.com
Includes FAQs, tube data sheets, tube substitutions, and tubes vs. transistors.
http://www.acadia.net/michelle/tubes.htm
Frederick W. Chesson presents one of the best military VT- tube to commercial tube conversion tables.
http://pages.cthome.net/fwc/VT.HTM
Broad variety of information on line from The Tone Lounge.
http://www.tone-lizard.com/Tube_Testers.html
Tube data and audio amplifier schematics online.
http://www.triodeel.com/tubedata.htm
How to use them and how they work. List of tubes and what they are used for.
http://www.vacuumtube.com/FAQ.htm
Tube data, info and links. From the Netherlands.
http://www.fust-electronica.nl/tubeinfo.htm
Online data for many tubes.
http://www.nd2x.net/tube-1.html