The assessment of endothelial function: From research into clinical practice - Flammer, A J; Anderson, T; Celermajer, D S; Creager, M A; Deanfield, J; Ganz, P; Hamburg, N M; Lüscher, T F; Shechter, M; Taddei, S; Vita, J A; Lerman, A (Circulation, 2012)