MacClellan LR, Howard TD, Cole JW, Stine OC, Giles WH, O'Connell JR, Wozniak MA, Stern BJ, Mitchell BD, Kittner SJ. Relation of candidate genes that encode for endothelial function to migraine and stroke: the Stroke Prevention in Young Women study. Stroke. 2009 Oct; 40(10):e550-7.