1. Abrams J (1978) Current concepts of the genesis of heart sounds. I. First and second sounds. JAMA 239: 2787
2. Brooks N, Leech G, Leatham A (1979) Factors responsible for normal splitting of first heart sound. High-speed echophonocardiographic study of valve movement. Br Heart J 42: 695
3. Brooks N, Leech G, Leatham A (1979) Complete right bundle branch block. Echophonocardiographic study of first heart sound and right ventricular contraction times. Br Heart J 41: 637
4. Burggraf GW, Craige E (1974) The first heart sound in complete heart block. Circulation 50: 17
5. Burggraf GW (1981) The first heart sound in left bundle branch block: An echophonocardiographic study. Circulation 63: 429