1. National Cancer Institute. The Occurrence of Tumors in Domestic Animals. Bethesda, Maryland: National Institutes of Health; 1980
2. Wells HG, Slye M, Homes HF. Comparative pathology of cancer of the alimentary canal, with a report of cases in mice. American Journal of Cancer Research. 1938;33:223-238
3. Doll R, Peto R. The causes of cancer: Quantitative estimates of avoidable risks of cancer in the United States today. Journal of the National Cancer Institute. 1981;66:1191-1308
4. Vietnam - Global Cancer Observatory, 2018 704 Viet-Nam-fact-sheets. International Agency for Research on Cancer. 2019. Available from: https://gco.iarc.fr/today/data/factsheets/populations/704-viet-nam-fact-sheets.pdf
5. GSO. Socio-Economic Statistical Data of 671 Districts, Towns, and Cities under the Authority of Provinces in Vietnam. Hanoi: Statistical Publishing House; 2006