Perrier, J.-Y.Sipper, M.Zahnd, J.2004-11-302004-11-302004-11-30199610.1016/0167-2789(96)00091-7https://infoscience.epfl.ch/handle/20.500.14299/177639WOS:A1996VL92400001Toward a viable, self-reproducing universal computertext::journal::journal article::research article