@Article{ls_leimeister,
  author = {Berkovich, M. and Leimeister, J. M. and Krcmar, H.},
  title  = {Requirements Engineering for Product Service Systems - A State of the Art Analysis},
  journal = {Business & Information Systems Engineering (BISE)},
  year   = {2011},
  number = {6},
  url    = {http://pubs.wi-kassel.de/wp-content/uploads/2013/03/JML_315.pdf},

  const  = {\ text}
}