That is an Eastern European tube brand. Sort of new, considered by many tubophiles as not very good, therefore, not mentioned in any of those specialty tube threads. These tubes you mention, are old production American or Western European tubes. It seems as if production and quality gets progressively worse, as the tubes are newer from a time stand point. Should be able to get some sort of decent NOS tubes for about $100 a pair....Not necessarily the cheapest, but that sort of tubes that you mention, the famous ones like the Bugleboys, Siemens and others are being hoarded by tubophiles as you speak...which makes the prices go up and up and up. A good pair, with good specs should last you about 9 years with about 3 hours of use everyday, or so I was told.
