There is also the concerto Hindemith wrote for Wittenstein, which he
never played, believed lost until it turned up quite recently in a cache
of material from Wittgenstein's estate in a farmhouse in Pennsylvania,
I think.

This was discussed in the press within the last several months; I regret
that I can't provide more accurate information.

I'll vouch for the high quality of the Schmidt LH piano chamber music;
the Theater Chamber Players, for whom I conduct here in Washington,
performed quite a bit of it with Leon Fleisher in his left-hand-only
days; I remember with pleasure particularly a big piano quintet [about
an hour in duration!] with clarinet.

Best wishes,

Joel Lazar
Bethesda MD