Cherenkova, L. V.
Sokolova, L. V.
Article History
Received: 28 March 2019
Revised: 17 May 2019
Accepted: 3 August 2019
First Online: 13 May 2020
COMPLIANCE WITH ETHICAL STANDARDS
: <i>Conflict of interest.</i> The authors declare that they have no conflict of interest related to the publication of this article.
: <i>Statement of compliance with standards of research involving humans as subjects</i><b><i>.</i></b> All studies were carried out in accordance with the principles of biomedical ethics formulated in the 1964 Helsinki Declaration and its later amendments and approved by the Ethics Committee of St. Petersburg State University (St. Petersburg). Parents of each child participating in the study provided voluntary written informed consent signed by them after explaining the potential risks and benefits, as well as the nature of the forthcoming study.