1. Codex Standards. www.fao.org/fao-who-codexalimentarius/standards/en/. Accessed September 2017.
2. World Health Organization 2009. NMH Fact sheet January 2010. http://www.who.int/nmh/publications/fact_sheet_cancers_en.pdf. Accessed August 2017.
3. Food and cancer. http://www.news_medical.net. Accessed August 2017.
4. Environmental causes of cancer. May 7, 2006. http://www.bu.edu/lovecanal/workshop/PresentRC0507.pdf
5. What causes cancer? Limpopo Department of Health and Social Development. http://www.dhsd.limpopo.gov.za/docs/What%20is%20Cancer.pdf. Accessed August 2017.