Author contribution: Pavlov ChS developed a concept and structure of the article, issued conclusions and finalized the article; Kovalevskaya VI made a significant contribution into the article concept, studied the literature sources, analyzed data and prepared the article. All the authors approved the final version of the article; Volel BA, Litvinova TM carried out scientific management, developed the article concept, finalized the text, finally approved the published version of the article.