Patel AG, Clark T, Oliver R, Stecker EC, Shapiro MD, Stajduhar K, Kron J, McAnulty JH, Chugh SS. Anomalous midline common ostium of the left and right inferior pulmonary veins: implications for pulmonary vein isolation in atrial fibrillation. Circ Arrhythm Electrophysiol. 2008 Dec; 1(5):407-8.