1. The (generalized) post correspondence problem with lists consisting of two words is decidable;Ehrenfeucht;Theoret. Comput. Sci.,1982
2. A property of three-element codes;Karhumäki,1984
3. About intersection of two free monoïds generated by two elements;Karhumäki;Semigroup Forum,1984
4. Equations dans les Monoïdes Libres;Lentin,1972
5. A combinatorial problem in the theory of free monoïds;Lentin,1967