4) Ohkita, K., and K. Fukushima, Japan Plastics, 3, (3), 6; (4), 25 (1969).
5) Ohkita, K., I. Tsubata, and N. Takashina, 10th Biennial Conf. on Carbon (Co-sponsored by the American Carbon Committee and Lehigh University), Summary of Papers, p. 237 (1971) Pennsylvania, U. S. A.