1. M. E. Della Stella and C. Guido, Associativity, Commutativity and symmetry in residuated structures, Order, 30 (2013), 363–401.
2. M. E. Della Stella and C. Guido, Extended-order algebras and fuzzy implicators, Soft Computing, 16 (2012), 1883–1892.
3. N. Galatos, P. Jipsen, T. Kowalski and H. Ono, Residuated Lattices: An Algebraic Glimpse at Substructural Logics, Elsevier, 2007.
4. C. Guido and P. Toto, Extended-order algebras, Journal of Applied Logic, 6 (2008), 609–626 .
5. K. Iséki and S. Tanaka, An introduction to the theory of BCK-algebras, Math. Japonica, 23 (1978), 1–26.
6. Y. C. Kim and J. M. Ko, Some properties of extended order algebras, Korean J. Math., 21 (2013), 63–73.
7. Y. C. Kim and J. M. Ko, Weak extended order algebras having adjoint triples, Korean J. Math., 21 (2013), 351–363.
8. H. Rasiowa, An algebraic approach to non-classical logics, Studies in Logic and the Foundations of Mathematics, 78, Amsterdam, 1974.
9. E. Sameri and R. A. Borzooei, Extended implicative groupoids, Journal of intelligent and fuzzy systems, 40 (2021), 1261–1275.
10. E. Sameri, R. A. Borzooei and D. E. Bagha, Filter theory of extended implicative groupoids, Soft Computing 25 (2021), 14499–14508.
11. A. WroĊski, BCK-algebras do not form a variety, Math. Japonica, 28 (1983), 211–213.