Early use of calf pulmonary surfactant in late preterm and full-term infants with respiratory distress syndrome：a randomized controlled trial
ZHOU Wen-Li, ZHOU Qi, LI Cong, WU Hui
CJCP . 2014, (3): 285 -289 .  DOI: 10.7499/j.issn.1008-8830.2014.03.014