1. Takagi, T., Yamada, I., Kunori, M., Kobiyama, S.: Proceedings of the 2nd International Conference on Ion Sources. pp. 790?795. Vienna: Österreichische Studiengesellschaft für Atomenergie GmbH 1972
2. Yamada, I., Takaoka, H., Inokawa, H., Usui, H., Cheng, S.C., Takagi, T.: Thin Solid Films92, 137 (1982)
3. Takagi, T.: Material Research Society Symposium Proceedings. Vol. 27, pp. 501?511. Pittsburg, Pennsylvania: Materials Research Society 1984
4. Yamada, I., Takaoka, H., Usui, H., Takagi, T.: J. Vac. Sci. Technol. A4, 722 (1986)
5. Stein, G.D.: In: Proceedings of the International Ion Engineering Congress ? ISIAT '83 & IPAT '83 ?, Kyoto, Takagi, T. (ed.), pp. 1165?1176B. Tokyo: Inst. Elec. Eng. of Japan 1983