Question:
Which employer did Jerzy Neyman work for in May, 1929?

Context:
 Jerzy Neyman works for Nencki Institute of Experimental Biology from Jan, 1928 to Jan, 1934. 
 Jerzy Neyman works for University of California, Berkeley from Jan, 1938 to Jan, 1981. 
 Jerzy Neyman works for University College London from Jan, 1934 to Jan, 1938.

Answer:
Nencki Institute of Experimental Biology