Jia Lee Ferdinand Peper Susumu Adachi Kenichi Morita An Asynchronous Cellular Automaton Implementing 2-State 2-Input 2-Output Reversed-Twin Reversible Elements. 67-76 2008 ACRI http://dx.doi.org/10.1007/978-3-540-79992-4_9 conf/acri/2008 db/conf/acri/acri2008.html#LeePAM08