This is an open access journal which means that all content is freely available without charge to the user or his/her institution. Users are allowed to read, download, copy, distribute, print, search, or link to the full texts of the articles, or use them for any other lawful purpose, without asking prior permission from the publisher or the author. This is in accordance with the BOAI definition of open access, while with the guidelines of the Ministry of Science and Higher Education implementing the policy of open access to publications and research results financed from public funds, articles in our issues are made available on the principles of Open Access – CC BY-NC-ND 3.0 PL.