1. 1) Japan Radioisotope Association: Statistics on the use of radiation in Japan , pp. 1-5 (2005)
2. 2) Agency of Natural Resources and Energy: Koureberu houshaseihaikibutu no shobun no anzensei nituite kangaete mimasenka , pp.5-8 (2006)
3. 3) Y. Takeuchi: Takousitsutai no seishitsu to sono ouyougijyutsu, Fuji Tekunoshisutemu (Tokyo), pp. 1132-1146 (2001)
4. 4) H. Koyama, et al.: Bulletin of Tokyo Metropolitan Industrial Technology Research Institute, 3, pp. 111-112 (2000)
5. 5) H. Koyama, et al.: Bulletin of Tokyo Metropolitan Industrial Technology Research Institute, 5, pp. 81-84 (2002)