O. I. Bishko Ivan Franko National University of Lviv Ukraine
N. P. Harasym https://orcid.org/0000-0002-6102-4271 Ivan Franko National University of Lviv Ukraine
D. I. Sanagursky https://orcid.org/0000-0002-8998-7117 Ivan Franko National University of Lviv Ukraine