1. Feigenbaum H: Echocardiography. Philadelphia Lea & Febiger 1972
2. Popp RL Harrison DC: The use of ultrasound in cardiac diagnosis. In Non-Invasive Technics in Cardiac Evaluation edited by Weissler AM. New York Grune & Stratton 1974
3. Popp RL Harrison DC: Cardiac chamber size and volume: Echographic measurement of cardiac chamber dimensions volume and ventricular function. In Ultrasound in the Diagnosis of Cardiovascular-Pulmonary Disease edited by Joyner CR. Chicago Year Book Medical Publishers 1974
4. Wells PNT: Physical Principles of Ultrasonic Diagnosis. London Academic Press 1969
5. Resolution problems in echocardiology: a source of interpretation errors