@unpublished{WilkeSandhaas2013,
  author  = {Andreas Wilke and Anna Sandhaas},
  title   = {Enzymatic pretreatment of biogas feedstock – a possibility to increase the biogas yield?},
  institution = {Fakult{\"a}t Maschinenbau und Verfahrenstechnik (M+V)},
  year    = {2013},
  language  = {en}
}