1) World Health Organization, “Cancer Pain Relief,” 2nd ed., 1996.
2) Center for Cancer Control and Information Services, National Cancer Center: 〈http://ganjoho.jp/public/statistics/pub/statistics01.html〉, cited 19 August, 2015.
3) Yodogawa Christian Hospital, “Palliative Care Manual,” 5th ed., Saishin Igakusha, Osaka, 2008.
4) Takeda F., Pain Clinic, 1, 83-89 (1986).
5) Ministry of Health, Labour and Welfare, 〈http://www.mhlw.go.jp/stf/houdou/0000051607.html〉, cited 19 August, 2015.