Evaluation of Serum Cortisol Levels in a Relatively Large and Mature Group of Ventilated and Nonventilated Preterm Infants with Respiratory Distress Syndrome - Gunes, Tamer; Koklu, Esad; Ozturk, Mehmet Adnan; Koklu, Selmin; Cetin, Neside (American Journal of Perinatology, 2006)