Lilienfeld, Julius Edgar, "Method and apparatus for controlling electric current" U.S. Patent 1745175 1930-01-28 (filed in Canada 1925-10-22, in US 1926-10-08).
Lilienfeld, Julius Edgar, "Method and apparatus for controlling electric current" U.S. Patent 1745175 1930-01-28 (filed in Canada 1925-10-22, in US 1926-10-08).