@article{Bhattacharya:7271,
      author        = "Bhattacharya, S. and Lefèvre, L. and Chatzistergos, T.
                       and Hayakawa, H. and Jansen, M.",
      title         = "{Rudolf Wolf to Alfred Wolfer: The Transfer of the
                       Reference Observer in the International Sunspot Number
                       Series (1876–1893)}",
      year          = "2024",
}