1. Katz LN, Pick A. Clinical electrocardiography. The arrhythmias. Philadelphia: Lea & Febiger; 1956. p. 169, 170, 201.
2. Fisch C. Electrocardiography of arrhythmias. Philadelphia: Lea & Febiger; 1990. p. 152, 160.
3. Marriott's practical electrocardiography;Wagner,2001
4. Ventricular premature systoles with postponed compensatory pause;Langendorf;Am Heart J,1953
5. Pick A, Langendorf R. Interpretation of complex arrhythmias. Philadelphia: Lea & Febiger; 1979. p. 6, 11.