1. 1) N. Murofushi, TANSO 2011 [No. 248] 105-111 [in Japanese].
2. 3) N. Iwashita, Zairyo Shiken Gizyutsu (Journal of Material Testing Research Association of Japan) 55 (2011) 76-80 [in Japanese].
3. 4) N. Iwashita, Carbon2011, Shanghai, China, 2011.7.25-29, No. 154.
4. 5) T. Maruyama, M. Eto and T. Oku, Carbon 25 (1987) 723-726.
5. 6) S. Mrozowski, Proceedings of First and Second Conference of Carbon (1956) p. 195, The Waverly Press, New York