Question:
Which employer did Leopold Vietoris work for in Jul, 1928?

Context:
 Leopold Vietoris works for University of Vienna from Jan, 1922 to Jan, 1927. 
 Leopold Vietoris works for TU Wien from Jan, 1928 to Jan, 1930. 
 Leopold Vietoris works for Graz University of Technology from Jan, 1920 to Jan, 1922.

Answer:
Question:
Which employer did Leopold Vietoris work for in Jul, 1928?

Context:
 Leopold Vietoris works for University of Vienna from Jan, 1922 to Jan, 1927. 
 Leopold Vietoris works for TU Wien from Jan, 1928 to Jan, 1930. 
 Leopold Vietoris works for Graz University of Technology from Jan, 1920 to Jan, 1922.

Answer:
user
TU Wien
assistant
Question:
Which employer did Leopold Vietoris work for in Jul, 1928?

Context:
 Leopold Vietoris works for University of Vienna from Jan, 1922 to Jan, 1927. 
 Leopold Vietoris works for TU Wien from Jan, 1928 to Jan, 1930. 
 Leopold Vietoris works for Graz University of Technology from Jan, 1920 to Jan, 1922.

Answer:
user
University of Vienna
Graz University of Technology
assistant
Question:
Which employer did Leopold Vietoris work for in Jul, 1928?

Context:
 Leopold Vietoris works for University of Vienna from Jan, 1922 to Jan, 1927. 
 Leopold Vietoris works for TU Wien from Jan, 1928 to Jan, 1930. 
 Leopold Vietoris works for Graz University of Technology from Jan, 1920 to Jan, 1922.

Answer:
user
TU Wien
assistant