@TECHREPORT{mvc02,
  author = "Macia, H. and Valero,V. and Cuartero,F.",
  title = "A Congruence Relation in Finite sPBC",
  institution = "UCLM",
  year = "2002",
  number = "DIAB-02-01-31",
  note = "http://www.info-ab.uclm.es/sec-ab/Tecrep/reportcong.pdf"
}