1. Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
2. University of North Carolina School of Medicine, Chapel Hill, North Carolina
3. Division of Pulmonary and Critical Care Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
4. Health Sciences Library, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
5. Division of Pediatric Cardiology, Department of Pediatrics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina