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Helmerhorst, Frans M., Huib AAM Van Vliet, Twina Gornas, M J. Finken, and David A. Grimes. "Intra‐uterine Insemination Versus Timed Intercourse or Expectant Management for Cervical Hostility in Subfertile Couples." Cochrane Database Syst Rev 2005.

Helmerhorst, Frans M., et al. "Intra‐uterine Insemination Versus Timed Intercourse or Expectant Management for Cervical Hostility in Subfertile Couples." Cochrane Database Syst Rev 2005.