1. Hamilton B. E. y Thomson J. K., The Heart in Pregnancy and the Childbearing Age. Little Brown and Company, Boston, 1941.
2. Jensen J., The Heart in Pregnancy C. V. Mosby and Company. St. Louis, 1938.
3. Stander H. J., Textbook of Obstetrics. D. Appleton-Century. Company. New York, 1945.
4. Grollmann A., The Cardiac Output of Man in Health and Disease. Charles C. Thomas, Editor, Baltimore, 1932.
5. Alward H. C., Observations on the Vital Capacity During the Last Month of Pregnancy and Puerpe-rium. American Journal of Obstetrics and Gynecology, 20-373-381, 1930.