Reference:
Topp C.W., Østergaard S.D., Søndergaard S., & Bech P. (2015). The WHO-5 Well-Being Index: A Systematic Review of the Literature. Psychotherapy and Psychosomatics, 84, 167-176.
WHO. (1998). Wellbeing Measures in Primary Health Care/The Depcare Project. WHO Regional Office for Europe: Copenhagen.
https://www.corc.uk.net/outcome-experience-measures/the-world-health-organisation-five-well-being-index-who-5/