@Book{VilAloVal96,
  author = 	 {{Vilares Ferro}, Manuel  and {Alonso Pardo}, {Miguel Angel} and
                  {Valderruten Vidal}, Alberto},
  title = 	 {Programaci\'on L\'ogica (segunda edici\'on)},
  publisher = 	 {Editorial T\'orculo},
  year = 	 {1996},
  address = 	 {Santiago de Compostela, Spain},
  edition = 	 {2nd},
  ISBN = 	 {84-89641-18-8},
}