[1] R. A. Borzooei and M. Bakhshi, Some results on hyper BCK-algebras, Quasi-groups and Related Systems 11 (2004), 9-24.
[2] Y. B. Jun, X. L. Xin, E. H. Roh, and M. M. Zahedi, Strong hyper BCK-ideals of hyper BCK-algebra, Math. Jap. 51(3) (2000), 493-498.
[3] Y. B. Jun, M. M. Zahedi, X. L. Xin, and R. A. Borzooei, On hyper BCK-algebra,Italian J. Pure App. Math., Oxford Ser. 10 (2000), 127-136.
[4] F. Marty, Sur une generalization de la notion de groupe, 8th Congress Math. Scandinaves, Stockholm (1934), 45-49.
[5] S.M. Mostafa, M.A. Abd-Elnaby and M.M.M. Yousef, Fuzzy ideals of KU-Algebras, Int. Math. Forum, 63(6) (2011) 3139-3149.
[6] C.Prabpayak and U.Leerawat, On ideals and congruence in KU-algebras, scientia Magna international book series, 5(1)(2009), 54-57.
[7] C.Prabpayak and U.Leerawat,On isomorphisms of KU-algebras,scientia Magna international book series,5(3)(2009),25-31.
[8] N.Yaqoob, S.M.Mostafa and M.A.Ansari, On cubic KU-ideals of KU-algebras, ISRN Algebra, (2013) Article ID935905, 10 pages.
[9] M. M. Zahedi, R. A. Borzoei, Y. B. Jun and A. Hasankhani, Some results on hyper K-algebras,Scientiae Mathematicae 3(1) (2000), 53-59.