Zimmermann, Marc; Testuz, Ariane; Schmutz, Mathieu; Burri, Haran (2009). Narrow-complex tachycardia with cycle length alternans: what is the mechanism? Heart rhythm, 6(8), pp. 1238-9. New York, N.Y.: Elsevier 10.1016/j.hrthm.2008.08.004