@techreport{WaKlW08b,
  author = {Wagner, R. and Klaus, M.},
  title = {Challenges and Examples of Mobile Direct Marketing},
  year = {2008},
  number = {2}
}

@incollection{WaKlC08a,
  author = {Wagner, R. and Klaus, M.},
  title = {Cultural Impacts on the Spread of Mobile Commerce: An International Comparison},
  booktitle = {Handbook of Research on Mobile Business},
  publisher = {IGI},
  year = {2008},
  pages = {245 - 259},
  edition = {2},
  url = {http://www.igi-global.com/downloads/pdf/Unhelkar245.pdf}
}

@incollection{WaKlC08b,
  author = {Wagner, R. and Klaus, M.},
  title = {Mobile Direct Marketing},
  booktitle = {Handbook of Research on Mobile Business},
  publisher = {IGI},
  year = {2008},
  pages = {269 - 281},
  edition = {2},
  url = {http://books.google.de/books?hl=de&lr=&id=JlpFnu8hMK4C&oi=fnd&pg=PA269&dq=martin+klaus+%22ralf+Wagner%22&ots=GXB0O_sNC_&sig=Jdr05yCvx_U5h4YlXX9EGVWOioU#PPA269,M1}
}

@techreport{WaKlW08a,
  author = {Wagner, R. and Klaus, M.},
  title = {The Spread of Mobile Commerce: An Inter-Cultural Comparison},
  year = {2008},
  number = {4},
  url = {http://books.google.de/books?hl=de&lr=&id=JlpFnu8hMK4C&oi=fnd&pg=PA245&dq=%22martin+klaus%22+%22ralf+wagner%22&ots=GXB0O_sQAV&sig=7582ynvDxyqaAmisdbVdaryUkGk}
}