Fung, M.-C., and C. Jackson. “When Feeling Positive Is Being ‘in the zone’: How Challenge Optimality Causes Changes in Positive Affect and Flow”. Cyberpsychology: Journal of Psychosocial Research on Cyberspace, vol. 18, no. 4, Sept. 2024, p. Article 7, doi:10.5817/CP2024-4-7.