Bird was at his zenith in 47' and 48'. I have the recordings from the Onyx club, which are from either April or September. Not sure of the actual month. I've seen both months listed. But I believe this is the only recording either studio or live from 48'. I think there may have been a musician's strike around this time, but despite the poor sound, Bird is brilliant on all these sets. The takes on the live music, albeit not much longer in length then a studio take, exhibits why other musicians saw him as their prophet.