【作者】Yang C, Cai J, Geng Y, Gao Y. 
    【文章标题】Multiple-dose and double-dose versus single-dose administration of methotrexate for the treatment of ectopic pregnancy: a systematic review and meta-ysis.
    【期刊名,年份,卷(期),起止页*****】Reprod Biomed Online. 2017 Apr;34(4):383-391.