00587naa#a2200169#i#450# EN\\bibl\95078 20250516070104.5 2949-1258 20250218b2025####ek#y0engy0150####ca RU Why one can't «motivate teenagers to study»: existential and academic motivation of adolescents aged 15–16 Journal article Vladivostok Vladivostok State University 2025 9 с. Journal article local Философия. Психология. 1 Chernyavskaya Valentina S. ojkum.editorum.ru