@article{Ehlers2007,
  author    = {J{\"u}rgen Ehlers},
  title     = {Modelle in der Physik},
  url       = {http://edoc.bbaw.de/oa/series/reNu9MKM4Lndw/PDF/27c64ZzkzmKXk_478.pdf},
  year      = {2007},
}