P.M. Dovgalyuk - Ph.D., Assistant professor in Yaroslav-the-Wise Novgorod State University. E-mail: Pavel.Dovgaluk@ispras.ru
N.I. Fursova - Student of Yaroslav-the-Wise Novgorod State University. E-mail: Natalia.Fursova@ispras.ru
D.S. Dmitriev - Student of Yaroslav-the-Wise Novgorod State University. E-mail: Denis.Dmitriev@ispras.ru