[sdiy] [OT] Tube manuals

[Toby Paddock]

A friend at work has some tube manuals he said he
would sell me, but neither of us has a clue for
how much. So I'm wondering if anyone
has a rough ballpark guess what they might be
worth?

RCA ELECTRON TUBE HANDBOOK HB-3
Dates on the data sheet seem to be 40's and 50's.
5 volumes in weird hinged spine (so they lay flat) smallish 4 ring
binders.
rec 1, rec 2, transmitting, general;cathode ray;storage,
  and photo;thy;ign;glow-dis;misc
As a guess, I'd rate them Very Good condition.
Stacked up, they are about 14 inches thick.

I didn't see anything on ebay even close,

Thanks,
Toby Paddock