1. Hitachi Research Lntmratory, 4026 Kuji, Hitachi, Ibaraki 319-12, Systems Engineering Division, IIitachi, Ltd., 4-6, Kanda-Surugadai, Chiyoda Tokyo 101
2. Hitachi Research Lntmratory, 4026 Kuji, Hitachi, Ibaraki 319-12
3. Hitachi Central Resenrch LAmratory, 1-280 Higashi-Koigakubo, Kokubunji, Tokyo 185