9Cao X, Zhang W, Gao G, et al. Randomized comparative trial in parous women of the frameless gynefix and the TCu380A intrauterine devices:long-term experience in a Chinese family planning clinic [ J ]. Eur J Contracept Reprod Health Care,2000,5 (2) :135 - 140.
10Dirk W, Istvan B, Biran A, et al. The frameless intrauterine system for long-term, reversible contraception:a review of 15 years of clinical experience [ J]. Obstet Gyneco! Res ,2003,29(3 ) : 164 - 173.
