1. Fujioka, K. and staff of the group, Daidohokusan Corp., private communication (1994)
2. Asano, K. and staff of the group, Arisawa Manufacturing Co., private communication (1994)
3. Kamioka, Y. and staff of the group, Toyo Sanso, private communication (1994)
4. Kannoto, Y. and staff of the group, Mitsubishi Heavy Industry, Ltd, private communication (1994)