@article{DierckeArltDenker2015,
  author    = {Andrea Diercke and Rainer Arlt and Carsten Denker},
  title     = {Digitization of sunspot drawings by Sporer made in 1861-1894},
  journal   = {Astronomische Nachrichten = Astronomical notes},
  volume    = {336},
  number    = {1},
  pages     = {53 -- 62},
  doi       = {10.1002/asna.201412138},
  year      = {2015},
}