1. Algebraic analysis of many valued logics;Chang;Trans Amer Math Soc,1958
2. Characterizations of pseudo - BCK algebras;Jun;Sci Math Jpn,2003
3. On axiom systems of propositional calculi XIV Japan;Imai;Proc Acad,1966
4. Metamathematics of fuzzy logic of Academy of Science of Czech Rep Technical report;Hájek;Inst Comp Science,1996
5. Deductive systems and annihilators of pseudo - BCK algebras Pure;Halaš;Ital Appl Math,2009