@InCollection{michlmayr:volunteers_over_time,
  author =       {Michlmayr, Martin and Robles, Gregorio and
                  Gonzalez-Barahona, Jesus M.},
  title =        {Volunteers in Large Libre Software Projects: A
                  Quantitative Analysis Over Time},
  pages =        {1-24},
  editor =       {Sowe, Sulayman K and Stamelos, Ioannis G. and
                  Samoladas, Ioannis},
  booktitle =    {Emerging Free and Open Source Software Practices},
  publisher =    {IGI Publishing},
  address =      {Hershey, PA, USA},
  year =         {2007},
}