A Case-Control Comparison of the Effectiveness of Betamethasone to Prevent Neonatal Morbidity and Mortality in Preterm Twin and Singleton Pregnancies - Battista, Leah; Winovitch, Kim C; Rumney, Pamela J; Davis, Elysia; Hagemann, Cristiane; Wing, Deborah A (American Journal of Perinatology, 2008)