@article{Aparicio:3579,
      author        = "Aparicio, A.J.P. and Lefèvre, L. and Gallego, M.C.  and
                       Vaquero, J.M.  and Clette, F.  and Bravo-Paredes, N. and
                       Galaviz, P. and Bautista, L.",
      title         = "{A Sunspot Catalog for the Period 1952-1986 from
                       Observations made at the Madrid Astronomical Observatory}",
      year          = "2018",
      note          = "arXiv:1812.01733",
}