@article{lipson2004once,
  title={Once More Unto the Breach: Co-evolving a Robot and its Simulator},
  author={Hod Lipson and Joshua Bongard},
  journal={Proceedings of the Ninth International Conference on the Simulation and Synthesis of Living Systems (ALIFE9)},
  pages={57-62},
  journalpage={http://www.cs.uvm.edu/~jbongard/papers/2004_ALife9.pdf},
  year={2004},
  citations={}
}