4.
Kushlev, K., Heintzelman, S. J., Lutes, L. D., Wirtz, D., Oishi, S., & Diener, E. (2017). ENHANCE: Design and rationale of a randomized controlled trial for promoting enduring happiness & well-being. Contemporary Clinical Trials, 52(1), 62-74. doi:10.1016/j.cct.2016.11.003.