[78-L] Early Supraphon LPs

[Brian Bashford]

Hi Everyone,
I've just come into possession of 3 early Czech Supraphon 10" LPs. The 
catalogue numbers are DM 5022,  DM 5032 and  DM 5399. The first appears to 
be dated 1950 and the other 2 are 1951.  All have similar light green 
gatefold sleeves with plain white backs. The cardboard sleeves appear to be 
stitched together  along the top and bottom seams.

My question is ... are these dates too early for Supraphon?  I'd been led to 
believe that they didn't start producing vinyl LPs until 1954.

Regards,
Brian B.