1. Duration of Systole in Electrocardiogram;Fridericia;Acta med. Scandinav.,1920
2. Zur Bewertung der relativen Systolendauer; über die Abhängigkeit der relativen Systolendauer des Gesunden vom Lebensalter;Schlomka;Ztschr. f. Kreislaufforsch.,1936
3. An Analysis of the Time Relations of Electrocardiograms;Bazett;Heart,1918
4. Effect of Pulse Rate on the Length of the Systoles and Diastoles of the Normal Human Heart in the Standing Position;Lombard;Am. J. Physiol.,1919
5. Studies in Variation of Length of Q-R-S-T Interval;Fenn;Arch. Int. Med.,1922