@article{UM_2012_20_3_a7,
     author = {Calda, Emil},
     title = {O p\v{r}esn\'em vyjad\v{r}ov\'an{\'\i}, d\r{u}le\v{z}itosti a dokazov\'an{\'\i} matematick\'ych v\v{e}t},
     journal = {U\v{c}itel matematiky},
     pages = {189--192},
     year = {2012},
     volume = {20},
     number = {3},
     language = {cs},
     url = {http://geodesic.mathdoc.fr/item/UM_2012_20_3_a7/}
}