Xiaoyu Song Guowu Yang Marek A. Perkowski Yuke Wang Algebraic Characterization of Reversible Logic Gates. 311-319 2006 39 Theory Comput. Syst. 2 http://dx.doi.org/10.1007/s00224-004-1166-2 db/journals/mst/mst39.html#SongYPW06