Pearce, E. ., Launay, J. ., Machin, A. ., & Dunbar, R. . (1969). Is group singing special? Health, well-being and social bonds in community-based adult education classes. Journal of Community & Applied Social Psychology, 26(6), 518-533. https://doi.org/10.1002/casp.2278 (Original work published 1969)