@Article{baldassarre03:_evolv_mobil_robot_able_displ_collec_behav,
  author = 	 {Baldassarre, G. and Nolfi, S. and Parisi, D.},
  title = 	 {Evolving Mobile Robots Able to Display Collective Behaviour},
  journal = 	 {Artificial Life},
  year = 	 2003,
  volume =	 9,
  number =	 3,
  pages =	 {255-267}
}