1. Annual per capita apparent consumption of tobacco products in the United States: 1900–1990;WJ Psoter;Prev Med,2001
2. International Agency for Research on Cancer (IARC) (2007) Smokeless tobacco and some tobacco-specific N-Nirtosamines, vol 89 of IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. World Health Organization International agency for Research on Cancer, Lyon, France: 89.
3. Smokeless tobacco and health in India and South Asia;PC Gupta;Respirology,2003
4. Department of Health and Human Services (DHHS) (1986) The Health Consequences of Using Smokeless Tobacco: A Report ofthe Advisory Committee to the Surgeon General. Washington, DC: Public Health Service. DHHS publication NIH 86-2874.
5. International Agency for Research on Cancer (IARC) (1985) Tobacco Habits Other than Smoking: Betel Quid and Areca Nut Chewing and Some Related Nitrosamines. Lyon, France: International Agency for Research on Cancer.