中华医学会.临床诊疗指南·妇产科学分册[M].北京:人民卫生出版社, 2007:183 .。Salim R, Zafran N,Nachum Z,et al . Employing nifedipine as a tocolytic agent prior to external cephalic version [ J ] . Acta Obstet Gynecol Scand,2008,87.