Georg Hafergut, Welz ('Elin' Aktiengesellschaft für elektrische Industrie, Vienna): Process and device for electric arc welding. US Patent No. US2269369A. Application 17 July 1939, Serial-No. 284,940, in Germany 2 December 1938. Retrieved on 13 June 2020.
Georg Hafergut, Welz ('Elin' Aktiengesellschaft für elektrische Industrie, Vienna): Process and device for electric arc welding. US Patent No. US2269369A. Application 17 July 1939, Serial-No. 284,940, in Germany 2 December 1938. Retrieved on 13 June 2020.