1. Griffith JM, Henry WL. An ultrasound system for combined cardiac imaging and Doppler blood flow measurement in man. Circulation 1978; 57(5):925–930.
2. Weyman AE, Hurwitz RA, Girod DA, Dillon JC, Feigenbaum H, Green D. Cross-sectional echocardiographic visualization of the stenotic pulmonary valve. Circulation 1977; 56(5):769–774.
3. Leblanc MH, Paquet M. Echocardiographic assessment of valvular pulmonary stenosis in children. Br Heart J 1981; 46(4):363–368.
4. Nishimura RA, Pieroni DR, Bierman FZ, Colan SD, Kaufman S, Sanders SP, et al. Second natural history study of congenital heart defects. Pulmonary stenosis: echocardiography. Circulation 1993; 87(2 Suppl):I73–I79.
5. Pellikka PA, Tajik AJ, Khandheria BK, Seward JB, Callahan JA, Pitot HC, et al. Carcinoid heart disease: clinical and echocardiographic spectrum in 74 patients. Circulation 1993; 87(4):1188–1196.