@article{ITA_1999__33_3_271_0,
     author = {Szepietowski, A.},
     title = {There is no complete axiom system for shuffle expressions},
     journal = {RAIRO - Theoretical Informatics and Applications - Informatique Th\'eorique et Applications},
     pages = {271--277},
     year = {1999},
     publisher = {EDP Sciences},
     volume = {33},
     number = {3},
     mrnumber = {1728427},
     zbl = {0951.68066},
     language = {en},
     url = {https://www.numdam.org/item/ITA_1999__33_3_271_0/}
}