Nazarkevych, Maria     Software development for protecting printed documents [Текст] / Maria Nazarkevych, Yurii Klishch, Roman Oliyarnik // Computer science and information technologies CSIT 2014 : proc. of the IX Intern. sci. and techn. conf., Nov. 18-22, 2014, Lviv, Ukraine / Min. of Education and Science of Ukraine, Lviv Politechniс Nat. Univ. — Lviv : Publ. Lviv Politechniс, 2014. — P. 79-80.