Lilienfeld, Julius Edgar, "Method and apparatus for controlling electric current" U.S. Patent 17,45,175 January 28, 1930 (filed in Canada 1925-10-22, in US October 8, 1926).
Lilienfeld, Julius Edgar, "Method and apparatus for controlling electric current" U.S. Patent 17,45,175 January 28, 1930 (filed in Canada 1925-10-22, in US October 8, 1926).