@article{Ior:06a,
  journal = {Soft Computing},
  volume = {12},
  title = {On BCK algebras: Part II: New algebras. The ordinal sum (product) of
           two bounded BCK algebras},
  author = {Iorgulescu, Afrodita},
  year = {2008},
  pages = {835--856},
  number = {9},
}