@ARTICLE {, title = {Matematické nástroje. Zaveď funkciu}, author = {Vrábel, Peter}, journal = {Obzory matematiky, fyziky a informatiky}, year = {2011}, volume = {40}, number = {3}, pages = {15--19}, issn = {1335-4981}, abstract = {The use of mathematical tool define a function is illustrated on solutions of various tasks in the paper.}, }