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Visser W, Wallenburg HC.Visser W, et al. Among authors: wallenburg hc.Baillieres Best Pract Res Clin Obstet Gynaecol. 1999 Mar;13(1):131-56. doi: 10.1053/beog.1999.0011.Baillieres Best Pract Res Clin Obstet Gynaecol. 1999.PMID: 10746098Review.