1. H. Monji, M. Aoki, H. Torii, H. Okinaka, United States Patent No. 4,629,487 (1986).
2. Y. Kashiwagi, M. Umetani, H. Kataoka, K. Inoue, S. Nakamura, S. Morimoto, United States Patent No. 6,009,728 (2000).
3. K. Hibino, M. Umetani, H. Kataoka, United States Patent No. 6,119,485 (2000).
4. K. Kuribayashi, M. Sakai, H. Monji, M. Aoki, H. Okinaka, H. Torii, United States Patent No. 4,685,948 (1987).
5. Ir-based multi-component coating on tungsten carbide by RF magnetron sputtering process