@InProceedings{robles_etal:volunteer_evolution,
  author =       {Robles, Gregorio and Gonzalez-Barahona, Jesus M. and
                  Michlmayr, Martin},
  title =        {Evolution of Volunteer Participation in Libre Software
                  Projects: Evidence from {D}ebian},
  editor =       {Scotto, Marco and Succi, Giancarlo},
  booktitle =    {Proceedings of the First International Conference on Open
                  Source Systems},
  pages =        {100-107},
  address =      {Genova, Italy},
  year =         {2005},
}