discogs has the additional information: licensed from musicrent inc.
and below this, licensed from hho ltd.
there is no indication whence this information was obtained.
the official ninasimone website either does not list, or has deliberately/accidentally fairly-well hidden any listings of cds of her music; and the various more-or-less official websites selling cds don't seem to be very bothered about the legality nor the ultimate origin of the tracks on compilations, generally.
i cannot tell from what i've been able to find - which is very little indeed - when these tracks were recorded, nor for which music corpse, nor whether these tracks were obtained legally, nor by whom.
So are these original 50s/60s/70s recordings, or could they actually be re-recordings made by Nina late in her life for small change? If these are the original versions, they would certainly have been in breach of UK copyright, which I think was still 50 years for sound recordings back in 1994, and all of Nina's work to that point was less than 50 years old, and some, like "Here Comes the Sun" and "My Way", recorded for RCA in 1971, were less than 25 years old!