1. The United Nations. Department of Economic and Social Affairs. Population division. World population prospects, the 2015 revision.
https://esa.un.org/unpd/wpp/Download/Standard/Population/
. Accessed 17 Mar 2017.
2. Ministry of Health, Labour and Welfare. Abridged life tables for Japan 2015.
http://www.mhlw.go.jp/english/database/db-hw/lifetb14/
. Accessed 17 Mar 2017.
3. Statics Bureau, Ministry of Internal Affairs and Communications. Population estimates by age (5-year age group) and sex.
http://www.stat.go.jp/english/data/jinsui/tsuki/
. Accessed 17 Mar 2017.
4. Center for Cancer Control and Information Services, National Cancer Center, Japan. Incidence of stomach cancer (National Estimates).
http://gdb.ganjoho.jp/graph_db/
. Accessed 17 Mar 2017.
5. Kunisaki C, Akiyama H, Nomura M, Matsuda G, Otsuka Y, Ono HA, et al. Comparison of surgical outcomes of gastric cancer in elderly and middle-aged patients. Am J Surg. 2006;191:216–24.