@article{JEDRZEJOWICZ198833,
    Author = {Jedrzejowicz, Joanna},
    File = {Infinite hierarchy of expressions containing shuffle closure operator - jedrzejowicz1988 - a - u.pdf},
    ISSN = {0020-0190},
    Journal = {Information Processing Letters},
    Keywords = {Shuffle operator, shuffle closure operator},
    Number = {1},
    Pages = {33--37},
    Title = {Infinite hierarchy of expressions containing shuffle closure operator},
    URL = {http://www.sciencedirect.com/science/article/pii/0020019088901408},
    Volume = {28},
    Year = {1988},
    bdsk-url-1 = {http://www.sciencedirect.com/science/article/pii/0020019088901408},
    bdsk-url-2 = {https://doi.org/10.1016/0020-0190(88)90140-8},
    date-added = {2020-10-23 16:39:59 +0200},
    date-modified = {2020-10-23 16:40:19 +0200},
    doi = {10.1016/0020-0190(88)90140-8}
}

@article{JEDRZEJOWICZ198833, Author = {Jedrzejowicz, Joanna}, File = {Infinite hierarchy of expressions containing shuffle closure operator - jedrzejowicz1988 - a - u.pdf}, ISSN = {0020-0190}, Journal = {Information Processing Letters}, Keywords = {Shuffle operator, shuffle closure operator}, Number = {1}, Pages = {33--37}, Title = {Infinite hierarchy of expressions containing shuffle closure operator}, URL = {http://www.sciencedirect.com/science/article/pii/0020019088901408}, Volume = {28}, Year = {1988}, bdsk-url-1 = {http://www.sciencedirect.com/science/article/pii/0020019088901408}, bdsk-url-2 = {https://doi.org/10.1016/0020-0190(88)90140-8}, date-added = {2020-10-23 16:39:59 +0200}, date-modified = {2020-10-23 16:40:19 +0200}, doi = {10.1016/0020-0190(88)90140-8} }