1. Administration for Community Living.Profile of older Americans. Accessed 2019 July 30.https://acl.gov/aging‐and‐disability‐in‐america/data‐and‐research/profile‐older‐americans.
2. Diversity and our common future: Race, ethnicity, and the older American;Treas J;Generations,2010
3. Evidence for a limit to human lifespan;Dong X;Nature,2016
4. Russian life expectancy hits record high. Accessed 2019 July 30.https://www.themoscowtimes.com/2017/06/29/russian‐life‐expectancy‐hits‐record‐high‐a58274.