@article{Keller1977,
  author    = {Gerhard Keller},
  title     = {Hydrologische Untersuchungen f{\"u}r den Rubbenbruchsee},
  journal   = {Osnabr{\"u}cker naturwissenschaftliche Mitteilungen},
  volume    = {5},
  pages     = {61 -- 71},
  year      = {1977}
}