@article{OlaPelPur:07,
  journal = {Studia Universitatis Babes--Bolyai, seria Mathematica},
  volume = {52},
  title = {On the completeness of the semihypergroups associated to binary
           relations},
  author = {Olaru, Hora\c tiu and Pelea, Cosmin and Purdea, Ioan},
  year = 2007,
  pages = {73--85},
  number = {2},
}