Prevalence and risk factors of preterm birth among singletons from 2013 to 2017 in Tongzhou district of Beijing
MA Hai-hui, JIN Chu-yao, WANG Hai-jun, LIU Zheng, LIN Li-zi, LIU Jue
journal1 . 2019, (6): 592 -596 .  DOI: 10.11852/zgetbjzz2018-0944