Kozlov, A.I., et al. “HORMONES AND PROSPECTS: PSYCHOLOGICAL AND ENDOCRINE CHARACTERISTICS OF CHRONIC ANXIETY AND STRESS AMONG SCHOOLCHILDREN AND STUDENTS OF THE ‘THREE RUSSIAS’”. Perm Federal Research Centre Journal, no. 4, Mar. 2016, pp. 97-105, https://journal.permsc.ru/index.php/pscj/article/view/PSCJ2015n4p10.