참고문헌
- Y. S. Huang, BCI-algebra, Science Press, Beijing, 2006.
- Y. B. Jun, K. J. Lee, and S. Z. Song, N-ideals of BCK/BCI-algebras, J. Chungcheong Math. Soc. 22 (2009), no. 3, 417-437.
- J. Meng and Y. B. Jun, BCK-algebras, Kyungmoon Sa Co., Seoul, 1994.