1. W.M. Thomas, E.D. Nicholas, J.C. Needham, M.G. Murch, P. Templesmith, C.J. Dawes, Friction Stir Butt Welding, Int. Patent App. PCT/GB92/02203 and GB Patent App. 9125978.8, December (1991);
2. U.S. Patent No. 5,460,317, October (1995).
3. Effects of friction stir welding on microstructure of 7075 aluminum