1. Bhargava, R.K: Cor pulmonale. New York: Futura Company 1973
2. Burkhardt, D: Zur Diagnostik des chronischen Cor pulmonale. Bern: Hans Huber 1972
3. Caird, F.I, Wilcken, D.E.L: The ECG in chronic bronchitis with generalized obstructive lung disease: Its relation to ventilatory function. Amer. J. Cardiol. 10, 5 (1962)
4. Calatajud, J.B, Abad, J.M, Khoi, N.B, Stanbro, W.W, Silver, H.M: P-Wave changes in chronic obstructive pulmonary disease. Amer. Heart J. 10, 5 (1962)
5. Chappell, A.G: The ECG in chronic bronchitis and emphysema. Brit. Heart J. 28, 517 (1966)