1. Automatic Sequences;Allouche,2003
2. Représentation géométrique de suites de complexité 2n+1;Arnoux;Bull. Soc. Math. France,1991
3. On the index of sturmian words;Berstel,1999
4. J. Berstel, Private communication, 2010.
5. Combinatorics on Words: Christoffel Words and Repetitions in Words;Berstel,2008