Tullio Ceccherini-Silberstein Wolfgang Woess Growth-sensitivity of context-free languages. 103-116 2003 307 Theor. Comput. Sci. 1 http://dx.doi.org/10.1016/S0304-3975(03)00095-1 db/journals/tcs/tcs307.html#Ceccherini-SilbersteinW03