Medykovskyy, Mykola     Methods of protection document formed from latent element located by fractals [Текст] / Medykovskyy Mykola, Piotr Lipinski, Troyan Oksana, Nazarkevych Maria // Computer science and information technologies CSIT 2015 : proc. of the Х Intern. scientific and techn. conf., 14-17 sept. 2015, Lviv, Ukraine / Min. of Education and Science of Ukraine, Lviv Polytechnic Nat. Univ. ; [відп. за вип. О. С. Стрямець]. — Lviv : Lviv Polytechnic Publ. House, 2015. — P. 70-72.