The sonatas are published by Barenreiter Verlag. The Echoes from Austria is published by Rongwen Music Inc of New York and the sole selling agent is Broude Brothers.
This, by the way, from the man who doesn't know much. Not!
Krenek was a most prolific composer, a good many of whose works are well worth the trouble investigating. Even the first two symphonies, composed by the time he was in his early 20s, deserve far more attention than they get anywhere, including his native Austria.
Best,
Alistair