@misc{Guncaga_Jan_Derivative_2009,
 author={Guncaga, Jan},
 type={artykuł},
 publisher={Wydawnictwo Akademii im. Jana Długosza w Częstochowie},
 title={Derivative of a function at a point and integral by professor Igor Kluvanek},
 address={Częstochowa},
 year={2009},
 language={eng},
}