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CHINESE JOURNAL OF OBSTETRICS AND GYNECOLOGY, Volume 36, Issue 4,2001, Pages 222-225, doi:10.3760/j.issn:0529-567X.2001.04.009
CHINESE JOURNAL OF OBSTETRICS AND GYNECOLOGY, Volume 36, Issue 4,2001, Pages 229-232, doi:10.3760/j.issn:0529-567X.2001.04.011
CHINESE JOURNAL OF OBSTETRICS AND GYNECOLOGY, Volume 36, Issue 4,2001, Pages 197-198, doi:10.3760/j.issn:0529-567X.2001.04.001