1. Decision problems for regular expressions with shuffle and shuffle closure operators;Araki;Trans. Inst. Electron. Commun. Eng. Japan,1981
2. Flow languages equal recursively enumerable languages;Araki;Acta Inform.,1981
3. Literal shuffle;Berard;Theoret. Comput. Sci.,1987
4. Nonfinite axiomatizability of shuffle inequalities;Bloom,1995
5. Nonfinite axiomatizability of the equational theory of shuffle;Ésik,1995