Oral direct thrombin inhibitor AZD0837 for the prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation: a randomised dose-guiding, safety and tolerability study of four doses of AZD0837 versus vitamin K antagonists - Lip, GYH; Rasmussen, LH; Olsson, SB (Eur Heart J, 2009)