Varenicline, an alpha4beta2 nicotinic acetylcholine receptor partial agonist, vs sustained-release bupropion and placebo for smoking cessation: a randomized controlled trial. - Gonzales D; Rennard SI; Nides M; Oncken C; Azoulay S; Billing CB; Watsky EJ; Gong J; Williams KE; Reeves KR; Varenicline Phase 3 Study Group; Gonzales, David; et al. (JAMA: Journal of the American Medical Association, 2006)