How can I find information about congress commitee chairs?

This House committee, McCormack-Dickstein, was named after its chairman and vice chairman, John W. McCormack and Samuel Dickstein. It was called the Special Committee on Un-American Activities Authorized to Investigate Nazi Propaganda and Certain Other Propaganda Activities. In 1934, it held public and private hearings in six cities, questioned hundreds of witnesses and collected testimony filling 4,300 pages. Its mandate was to get "information on how foreign subversive propaganda entered the U.S. and the organizations that were spreading it."