@article{Carrasco:3578,
      author        = "Carrasco, V.M.S.  and García-Romero, J.M. and Vaquero,
                       J.M. and Rodríguez, P. G. and Foukal, P. and Gallego, M.C.
                       and Lefevre, L.",
      title         = "{The umbra-penumbra area ratio of sunspots during the
                       Maunder Minimum}",
      year          = "2018",
}