1. Hofman JI, Christian R. Congenital heart disease in a cohort of 19,502 births with long term follow-up. Am J Cardiol 1978;42:641-647.
2. Lian ZH, Zach MM, Erickson JD. Paternal age and occurrence of birth defects. Am J Hum Genet 1986;39:648-660.
3. Mitchell SC, Korones SB, Berendes HW. Congenital heart disease in 56,109 births. Circulation 1971;43:323-332.
4. Ewigman BG, Crane JP, Frigoletto FD, LeFevre ML, Bain RP, McNellis D. RADIUS Study Group. Effect of prenatal ultrasound screening on perinatal outcome. N Engl J Med 1993;329:821-821.
5. Cullen S, Sharland GK, Allan LD, Sullivan ID. Potential impact of population screening for prenatal diagnosis of congenital heart disease. Arch Dis Child 1992;67:775-778.
6. Chitlin MD, Alpert JS, Armstrong WF, Aurigemma GP, Beller GA, Ryan TJ, et al. ACC/AHA guidelines for the clinical application of echocardiography: Executive summary. J Am Coll Cardiol 1997;29:862-879.
7. Hess DB, Flaker G, Aggarwal KB, Buchheit LC, Hess LW. In: Hess DB, Hess LW, editor. Fetal cardiac imaging. Fetal echocardiography 1999;Stamford: Appleton & Lange. 149-194.
8. Yagel S, Weissman A, Rotstein Z, manor M, Hegesh J, Achiron R, et al. Congenital heart defects: natural course and in utero development. Circulation 1997;96:550-555.
9. Abuhamad A. A practical guide to fetal echocardiography 1997;Philadelphia: Lippincott-Raven.
10. Comstock CH. Normal fetal heart axis and position. Obstet Gynecol 1987;70:255-259.
11. Shipp TD, Bromely B, Hornberger LK, Nadel A, Benacerraf BR. Levorotation of the fetal cardiac axis: a clue for the presence of congenital heart disease. Obstet Gynecol 1995;85:97-102.
12. Truesdell SC. In: Jaffe R, Bui TH, editor. Fetal cardiography. Textbook of fetal ultrasound 1999;New York: Parthenon Publishing Group. 153-173.
13. Friedman AH, Copel JA, Kleinman CS. Fetal echocardiography and fetal cardiology: Indications, diagnosis and managment. Seminars in perinatology 1993;17:76-88.