1. D.C. Kang, Z.R. Wang, S.D. Li, Q.M. Cheng, in: M. Kobayashi (Ed.), Proceedings of the Third International Conference on RoMP, 1984, IFS Ltd./North-Holland, p. 165.
2. M. Hayama, in: Proceedings of the First International Conference on RoMP, 1979, IFS Ltd., p. 207.