@misc{WetterBrueggingOrtmann2013,
  author    = {Wetter, Christof and Br{\"u}gging, Elmar and Ortmann, Jan},
  title     = {Groen Gas InNet; 1. Expertenworkshop InNet, Steinfurt April 2013},
  year      = {2013},
  language  = {mul}
}