Question:
Which employer did Johann Radon work for in Sep, 1922?

Context:
 Johann Radon works for University of Hamburg from Jan, 1919 to Jan, 1922. 
 Johann Radon works for University of Vienna from Jan, 1946 to Jan, 1956. 
 Johann Radon works for TU Wien from Jan, 1912 to Jan, 1913. 
 Johann Radon works for University of Greifswald from Jan, 1922 to Jan, 1925. 
 Johann Radon works for University of Innsbruck from Jan, 1945 to Jan, 1946. 
 Johann Radon works for University of Wrocław from Jan, 1928 to Jan, 1945. 
 Johann Radon works for University of Erlangen-Nuremberg from Jan, 1925 to Jan, 1928.

Answer:
University of Greifswald