According to the Internet source given below, Hans Erich Apostel was a German-born Austrian composer of classical music.
From 1916 to 1919 he studied piano, conducting and music theory in Karlsruhe with Alfred Lorenz. In 1920 he was Kapellmeister and Répétiteur at the Badisches Landestheater in Karlsruhe. He studied in Vienna with Arnold Schoenberg
from 1921 to 1925 and with Alban Berg from 1925 to 1935.
Apostel was active as a pianist, accompanist, and conductor of contemporary music in Austria, Germany, Switzerland and Italy.
||Hans Erich Apostel
||Biography by wikipedia.org.