@article{AUPO_1985__24_1_a0,
     author = {Rach\r{u}nek, Ji\v{r}{\'\i}},
     title = {Modal operators on ordered sets},
     journal = {Acta Universitatis Palackianae Olomucensis. Facultas Rerum Naturalium. Mathematica},
     pages = {9--14},
     publisher = {mathdoc},
     volume = {24},
     number = {1},
     year = {1985},
     mrnumber = {879015},
     zbl = {0621.06003},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/AUPO_1985__24_1_a0/}
}