Bell, S. ., Audrey, S. ., Gunnell, D. ., Cooper, A. ., & Campbell, R. . (2019). The relationship between physical activity, mental wellbeing and symptoms of mental health disorder in adolescents: a cohort study. The International Journal of Behavioral Nutrition and Physical Activity, 16(1), 138. https://doi.org/10.1186/s12966-019-0901-7 (Original work published 2019)