@book{arroyobook19,
  author = {Arroyo Guarde\~no, D. and D\'iaz Vico, J. and Hern\'andez Encinas, L.},
  title = {¿Qu\'e sabemos de? Blockchain},
  year = {2019},
  publishier = {Editorial Catarata},
  url = {https://www.catarata.org/libro/blockchain_94238/}
}