@article{AUPO_1980_19_1_a5,
     author = {Zedn{\'\i}k, Franti\v{s}ek},
     title = {On one definition of grammatical categories},
     journal = {Acta Universitatis Palackianae Olomucensis. Facultas Rerum Naturalium. Mathematica},
     pages = {75--87},
     year = {1980},
     volume = {19},
     number = {1},
     mrnumber = {0630370},
     zbl = {0471.68055},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/AUPO_1980_19_1_a5/}
}