Michelangelo Bucci Aldo de Luca Alessandro De Luca Luca Q. Zamboni On different generalizations of episturmian words. 23-36 2008 393 Theor. Comput. Sci. 1-3 http://dx.doi.org/10.1016/j.tcs.2007.10.043 db/journals/tcs/tcs393.html#BucciLLZ08