1. United Nations, Department of Economic and Social Affairs, Population Division. World Population Prospects 2019, Online Edition, Rev. 1, https://go.nature.com/3cFqF0R (2019).
2. Giridhar, G., Sathyanarayana, K. M. & James, K. S. in Population Ageing in India (eds. Giridhar, G. et al.) xvii–xxvi (Cambridge Univ. Press, 2014).
3. World Health Organization. Decade of Healthy Aging: Plan of Action, https://go.nature.com/3HjQOQS (14 December 2020).
4. International Institute for Population Sciences (IIPS) et al. Longitudinal Ageing Study in India (LASI) Wave 1, 2017–18, India Report, https://go.nature.com/2YOoDbk (2020).
5. University of Michigan. Health and Retirement Study, https://go.nature.com/3FfxeTW (2017).