@incollection{GeoIor:01c,
  title = {Pseudo-{BCK} algebras: an extension of {BCK} algebras},
  year = {2001},
  booktitle = {Combinatorics, computability and logic (Constan\c ta, 2001)},
  pages = {97--114},
  publisher = {Springer},
  address = {London},
  author = {Georgescu, George and Iorgulescu, Afrodita},
  series = {Springer Ser. Discrete Math. Theor. Comput. Sci.},
}