1. Rational Transductions and Context-Free Languages;Berstel,1979
2. Some recent results on square-free words;Berstel,1984
3. Motifs et répétitions;Berstel,1990
4. Square-free words and idempotent semigroups;Berstel,1983
5. On the centers of the set of weakly square-free words on a two letter alphabet;Carpi;Inform. Process. Lett.,1984