Question:
Where was Szolem Mandelbrojt educated in Mar, 1920?

Context:
 Szolem Mandelbrojt attended University of Warsaw from Jan, 1917 to Jan, 1919. 
 Szolem Mandelbrojt attended Paris-Sorbonne University - Paris IV from Jan, 1920 to Jan, 1923. 
 Szolem Mandelbrojt attended National University of Kharkiv from Jan, 1919 to Jan, 1920.

Answer:
Paris-Sorbonne University - Paris IV