1. W. M. Thomas, International Patent Application No. PCT/GB92 No. 9125978. 8 (1991).
2. C. J. Dawes et al., Welding J., 75-3 (1996) 41-45.
3. A. Kluken and M. Ranes, Svetsaren, 50-3 (1995) 13-15.
4. M. R. Johnsen, Welding J. 78-2 (1999) 35-39.
5. M. W. Mahoney, Welding & Joining, 1/2 (1997) 18-19.