1. Evolution of the electrocardiogram of healthy premature infants during the first year of life;Walsh;Acta paediat.,1963
2. Electrocardiographic studies in normal infants and children;Ziegler,1951
3. Nomenclature and criteria for diagnosis of diseases of the heart;Criteria Committee of the New York Heart Association,1953
4. P wave duration and P-R interval during the first week of life;Walsh;Brit. Heart J.,1963
5. Electrocardiographic intervals during the first week of life;Walsh;Am. Heart J.,1963