[1] HAO J.: A theorem for estimating the number of subalgebras in a finite BCK-algebra. Kobe J. Math. 3 (1986), 51-59. MR 0867802 | Zbl 0628.03040

[2] HU Q. P.-LI X.: On BCH-algebras. Math. Semin. Notes, Kobe Univ. 11 (1983), 313-320. MR 0769036 | Zbl 0579.03047

[3] HU Q. P.-LI X.: On proper BCH-algebras. Math. Japon. 30 (1985), 659-661. MR 0812016 | Zbl 0583.03050

[4] IMAI Y.-ISÉKI K.: On axiom systems of propositional calculi XIV. Proc. Japan Acad. Ser. A Math. Sci. 42 (1966), 19-22. MR 0195704 | Zbl 0156.24812

[5] ISÉKI K.: An algebra related with a propositional calculus. Proc. Japan Acad. Ser. A Math. Sci. 42 (1966), 26-29. MR 0202571 | Zbl 0207.29304

[6] ISÉKI K.: On BCI-algebras. Math. Semin. Notes, Kobe Univ. 8 (1980), 125-130. MR 0590171 | Zbl 0473.03059

[7] ISÉKI K.-TANAKA S.: Ideal theory of BCK-algebras. Math. Japon. 21 (1976), 351-366. MR 0441816 | Zbl 0355.02041

[8] ISÉKI K.-TANAKA S.: An introduction to the theory of BCK-algebras. Math. Japon. 23 (1978), 1-26. MR 0500283 | Zbl 0385.03051

[9] NEGGERS J.-JUN, YOUNG BAE-KIM, HEE SIK: On d-ideals in d-algebras. Math. Slovaca (To appear). MR 1728235

[10] NEGGERS J.-KIM, HEE SIK: On d-algebras. Math. Slovaca 49 (1999), 19-26. MR 1963442 | Zbl 0943.06012