Journal of Happiness Studies J Happiness Stud 22, 681–707 (2021) Journal of Happiness Studies, 22, 681-707. SPRINGER Kujanpaa, M, Syrek, C, Lehr, D, Kinnunen, U, Reins, J A & de Bloom, J 2021, ' Need Satisfaction and Optimal Functioning at Leisure and Work: A Longitudinal Validation Study of the DRAMMA Model ', Journal of Happiness Studies, vol. 22, no. 2, pp. 681-707 . https://doi.org/10.1007/s10902-020-00247-3