Engell, T., Kirkøen, B., Hammerstrøm, K. T., Kornør, H., Ludvigsen, K. H. & Hagen, K. A. (2020). Common Elements of Practice, Process and Implementation in Out-of-School-Time-Academic Interventions for At-risk Children: A Systematic Review. Prevention Science May;21(4):545-556 https://doi.org/10.1007/s11121-020-01091-w