i   http://www.nhsdirect.nhs.uk/articles/article.aspx?articleId=437§ionId=21757- smoking  (quitting) treatment
ii   www.ash.org.uk/html/factsheets/html/factsheets/basic01
iii  www.ash.org.uk/html/factsheets/html/fact11.html
iv The OTC Treatment Clinic: Smoking Cessation, Training Matters, November 2004
v   http://www.ash.org.uk/html/factsheets/html/fact10.html
vi  http://www.ash.org.uk/html/factsheets/html/fact08.html
vii http://www.ash.org.uk/html/factsheets/html/basic02.html
viii Perry DC, Davila-Garcia MI, Stockmeier CA, Kellar KJ. Increased nicotinic receptors in brains from smokers: membrane binding and autoradiography studies. Journal of Pharmacology and Experimental Therapeutics. 1999;289 (3):1545-1552. (Chronic exposure results in changes to the brain)
x Benowitz NL. (1998). Nicotine Pharmacology and Addiction. In: Benowitz NL (ed.)  Nicotine Safety and Toxicity, New York: Oxford University Press, pp 3-16. (Nicotine binds to several different nicotinic receptors)
x ASH website - http://www.ash.org.uk/html/factsheets/html/fact09.html
xi  www.primetheory.com
xii http://www.nhsdirect.nhs.uk/articles/article.aspx?articleId=437§ionId=21757 -Treatment