@Article{ authors = " Paula Puškárová, Štefan Zajac", title = "Innovation and Competitiveness of the Slovak Economy : New Evidence of International Impacts in the Knowledge Accumulation Process", journal = "International Journal of Management and Economics", issue = "2014 / Tom 42", pages = "81 - 97" }

@Article{ authors = " Leszek Wojtczak, Štefan Zajac", title = "On the Valenta Model and its Actuality II", journal = "Bulletin de la Société des Science et des Lettres de Łódź. Serie: Recherches sur les Déformations", issue = "2013 / Tom 63 / Numer 3", pages = "21 - 32" }