Knowledge, attitudes and practices of combined oral contraceptives in Tianjin obstetrics and gynecology personnels
HUO Yan, ZHANG Yujuan, WANG Jianmei△, YANG Jing, XIE Guohua
Tianjin Medical Journal . 2015, (3): 311 -314 .  DOI: 10.11958/j.issn.0253-9896.2015.03.024