* {{cite book|last=Steels|first=L|chapter=Towards a Theory of Emergent Functionality|editor-last1=Meyer|editor-first1=J.-A.|editor-last2=Wiloson|editor-first2=S. W.|title=From Animals to Animats: Proceedings of the First International Conference on Simulation of Adaptive Behavior|pages=451–461|location=Cambridge|publisher=MIT Press|date=1991}} | * {{cite book|last=Steels|first=L|chapter=Towards a Theory of Emergent Functionality|editor-last1=Meyer|editor-first1=J.-A.|editor-last2=Wiloson|editor-first2=S. W.|title=From Animals to Animats: Proceedings of the First International Conference on Simulation of Adaptive Behavior|pages=451–461|location=Cambridge|publisher=MIT Press|date=1991}} |