1. 1. BERSTEL J. and PERRIN D., Theory of Codes, Academic Press, Orlando, 1985.7970690587.68066
2. 2. ITO M., JURGENSEN H., SHYR H. J. and THIERRIN G., Anti-commutative Languages and n-codes (to appear in Applied Discrete Mathematics).10112740679.68140
3. 3. JURGENSEN H., SHYR H. J. and THIERRIN G., Codes and compatible partial orders on free monoids, Proceedings of the First International Symposium on OrderedAlgebraic Structures, Marseille 1984, Research and Exposition in Mathematics, Vol. 14, Helolermann Verlag Berlin, 1986.8914740611.06012
4. 4. LALLEMENT G., Semigroups and Combinatorial Applications, John Wiley, NewYork, 1979.5305520421.20025
5. 5. LOTHAIRE M., Combinatorics on Words, Encyclopedia of Mathematics and its Applications, Addison-Wesley, Reading, 1983.6759530514.20045