00637naa#a2200181#i#450# EN\\bibl\44175 20240503004844.5 2542-1840 20210519b2021####ek#y0engy0150####ca RU Development of Motivation Sphere in 14- and 15-Year-Olds Journal article Kemerovo Kemerovo State University 2021 9 с. Journal article local Образование. Воспитание. Обучение. Организация досуга. 37 Mikhailova Margarita Samandarovna Shamovskaya Tatiana V. vestnik-hss.kemsu.ru