1. Braunwald E. Valvular heart disease. In:Braunwald E (editor) Heart Disease. 4th edn. Philadelphia:WB Saunders, 1992:1007–77.
2. Carabello BA, Grossman W. Calculation of stenotic valve orifice area. In:Grossman W, Baim DS, editors. Cardiac Catheterization, Angiography and Intervention. 4th edn. Philadelphia:Lea &Febiger, 1992:152–65.
3. Weyman AE, Feigenbaum H, Dillon JC, Chang S Cross-sectional echocardiography in assessing the severity of valvular aortic stenosis. Circulation 1975;52:828–34.
4. DeMaria AN, Bommer W, Joye J, Lee G, Bouteller J, Mason DT. Value and limitations of cross-sectional echocardiography of the aortic valve in the diagnosis and quantification of valvular aortic stenosis. Circulation 1980;62:304–12.
5. Hatle L, Angelsen B. Doppler Ultrasound in Cardiology. 2nd edn. Philadelphia:Lea and Febiger, 1985.