By Mikio Nakahara (Kinki University, Osaka, Japan)
By Masamichi Ueno (Sophia University, Japan)
By Jiro Tsuji (Okayama University of Science, Japan)
By M. H. Aliabadi, etc., D.J. Cartwright (Bucknell University, USA), H. Nisitani (Kyushu University, Japan)