Elvinawanty, R. et al. 2022. Optimistic Thinking Training on Enhancement of Self-esteem in Street Children in the Komunitas Peduli Anak (KOPA) Medan. Journal of Psychology and Behavior Studies. 2, 1 (Jan. 2022), 17–23. DOI:https://doi.org/10.32996/jpbs.2022.2.1.3.