[1] Celani S.: 
A note on Homomorphisms of Hilbert Algebras. International Journal of Mathematics and Mathematical Science 29, 1 (2002), 55–61.  
MR 1892332 | 
Zbl 0993.03089[2] Chajda I., Halaš R., Zedník J.: 
Filters and Annihilators in Implication Algebras. Acta Univ. Palacki. Olomuc., Fac. rer. nat., Math. 37 (1998), 41–45.  
MR 1690472 | 
Zbl 0967.03059[3] Chajda I., Halaš R., Jun J. B. : 
Annihilators and deductive systems in commutative Hilbert algebras. Comment. Math. Univ. Carolinae 43, 3 (2002) 407–417.  
MR 1920517 | 
Zbl 1070.03043[4] Jun Y. B., Roh E. H., Meng J.: 
Annihilators in BCI-algebras. Math. Japonica 43, 3 (1996), 559–562.  
MR 1391864 | 
Zbl 0854.06028[5] Halaš R.: 
Annihilators of BCK-algebras. Czech. Math. Journal 53, 128 (2003), 1001–1007.  
MR 2018845[6] Halaš R.: 
Remarks on commutative Hilbert algebras. Math. Bohemica 127, 4 (2002), 525–529.  
MR 1942638 | 
Zbl 1008.03039[8] Pałasiński M.: 
Ideals in BCK-algebras which are lower semilattices. Math. Japonica 26, 2 (1981), 245–250.  
MR 0620466 | 
Zbl 0464.03056[9] Pałasiński M.: 
On ideal and congruence lattices of BCK-algebras. Math. Japonica 26, 5 (1981), 543–544.  
MR 0636589 | 
Zbl 0476.03064[10] Wei S. M., Jun Y. B.: 
Ideal lattices of BCI-algebras. Math. Japonica 44, 2 (1996), 303–305.  
MR 1416268 | 
Zbl 0878.06011