@misc{Wagner2006,
  author    = {Joachim Wagner},
  title     = {International Firm Activities and Innovation: Evidence from Knowledge Production Functions for German Firms},
  institution = {Fr{\"u}here Fachbereiche},
  series    = {University of L{\"u}neburg Working paper series in economics},
  number    = {25},
  type      = {researchpaper},
  year        = {2006},
}