Chiara Epifanio Alessandra Gabriele Filippo Mignosi Antonio Restivo Marinella Sciortino Languages with mismatches. 152-166 2007 385 Theor. Comput. Sci. 1-3 http://dx.doi.org/10.1016/j.tcs.2007.06.006 db/journals/tcs/tcs385.html#EpifanioGMRS07