Stoffa, Ján XXIV Didmattech 2011 : problems in teachers education. 2011, September 15th - 16th, Cracow. -- Kraków : Instytut Techniki UP, 2011. -- 269 s. -- ISBN : 978-83-7271-679-8. Wenta, Kazimierz. Vargová, Mária. Salata, E