[78-L] KBS Transcriptions, and more

[Malcolm]

Do we have someone on the list who's up on on transcription discs, 
specifically KBS (Keystone) 16" radio transcriptions? I am attempting to 
date some records from this manufacturer and keep coming up blank. I do 
know the trade style was first used in December 1940, and it was 
registered on Feb. 6, 1942, and that's about it.
Generally I am looking for label histories and dating guides, if 
possible, for most Radio Transcriptions - on any size disc - from c. 
1935 until they went out of use. Would the last issues be for AFRS/AFRTS 
(Armed Forces Radio Services / Armed Forces Radio & Television Services) 
records? I don't know the year, but I think it's late... maybe in the 
late 70s / early 80s?
There must be a reference work out there somewhere, besides Prof. Biel's 
thesis, about these discs and their producers.
But info is being very elusive. And I think it'll be a long slog through 
Billboard for me to find anything pertaining! I'd better get started...
Malcolm R