Impact of bronchopulmonary dysplasia, brain injury, and severe retinopathy on the outcome of extremely low-birth-weight infants at 18 months: results from the trial of indomethacin prophylaxis in preterms - Schmidt, B; Asztalos, E V; Roberts, R S; Robertson, C M; Sauve, R S; Whitfield, M FTrial of Indomethacin Prophylaxis in Preterms (TIPP) Investigators (JAMA, 2003)