Question:
Which employer did Wander Johannes de Haas work for in Dec, 1922?

Context:
 Wander Johannes de Haas works for Delft University of Technology from Jan, 1917 to Jan, 1922. 
 Wander Johannes de Haas works for University of Groningen from Jan, 1922 to Jan, 1924. 
 Wander Johannes de Haas works for Leiden University from Jul, 1924 to Sep, 1948.

Answer:
University of Groningen