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van der Pol JG, Wolf H, Boer K, Treffers PE, Leschot NJ, Hey HA, Vos A.van der Pol JG, et al. Among authors: treffers pe.Br J Obstet Gynaecol. 1992 Feb;99(2):141-3. doi: 10.1111/j.1471-0528.1992.tb14473.x.Br J Obstet Gynaecol. 1992.PMID: 1554667