@article{Veronig:6013,
      author        = "Veronig, Astrid M. and Jain, Shantanu and Podladchikova,
                       Tatiana and Pötzi, Werner and Clette, Frédéric",
      title         = "{Hemispheric sunspot numbers 1874-2020}",
      year          = "2021",
}