1. World Health Organization. Cancer Pain Relief: With A Guide To Opioid Availability. World Health Organization, 1996.
2. Stewart B, Christopher P. Wild. “World Cancer Report 2014.” World (2016).
3. Krishnan NM, Varghese C, Swaminathan R. “Cancer: current scenario, intervention strategies and projections for 2015.” NCHM Background papers-Burden of Disease in India; 2005. p. 219-25.
4. Breivik H, Cherny N, Collett B, de Conno F, Filbet M, Foubert AJ, et al. Cancer-related pain: A pan-European survey of prevalence, treatment, and patient attitudes. Ann Oncol 2009;20:1420-33.