1. 1) W. M. Thomas, E. D. Nicholas, J. C. Needham, M. G. Murch, P. Templesmith and C. J. Dawes: Friction Stir Butt Welding, Int Patent App PCT/GB92/02203 and GB Patent App 9125978.8, December 1991, US Patent No. 5 460, 317, October 1995.
2. 2) C. J. Dawes and W. M. Thomas: Weld. J. 75(1996) 41–45.
3. 3) S. H. C. Park, Y. S. Sato and H. Kokawa: Scr. Mater. 49(2003) 161–166.
4. 4) Y. Uematsu, K. Tokaji, Y. Tozaki, H. Shibata and T. Ohmune: Journal of JWS 25(2007) 224–229.
5. 5) J. Hagstrom and R. Sandstrom: Sci. Technol. Weld. Joining 2(1997) 199–208.