GROŠEK, Otokar (ed.) et al. Tatra Mountains Mathematical Publications : Number theory, algebra and cryptology '18. Bratislava : Slovak Academy of Sciences, 2019. 193 s. Available on Internet: <https://www.mat.savba.sk/ojs/index.php/TATRA/issue/view/37> ISSN 1210-3195. E*e-651/2019