Question:
Which employer did Warren Weaver work for in Mar, 1959?

Context:
 Warren Weaver works for University of Wisconsin–Madison from Jan, 1920 to Jan, 1932. 
 Warren Weaver works for Alfred P. Sloan Foundation from Jan, 1959 to Jan, 1964. 
 Warren Weaver works for California Institute of Technology from Jan, 1919 to Jan, 1920. 
 Warren Weaver works for United States Air Force from Jan, 1917 to Jan, 1919.

Answer:
Alfred P. Sloan Foundation