@article{Jansen1997,
  author    = {Jansen, Wolfgang},
  title     = {A note on the determination of the type of communication areas},
  year      = {1997},
  language  = {en}
}
@article{FeudelJansenKurthsetal.1997,
  author    = {Feudel, Ulrike and Jansen, Wolfgang and Kurths, J{\"u}rgen and Schwarz, Udo and Voss, Henning U.},
  title     = {Solar variability : simple models and proxy data},
  isbn      = {4-274-90187-4},
  year      = {1997},
  language  = {en}
}