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Mertens PL, Willemsen F, Houben AW, van Boven CP.Mertens PL, et al. Among authors: willemsen f.Ned Tijdschr Geneeskd. 1990 Jun 30;134(26):1258-61.Ned Tijdschr Geneeskd. 1990.PMID: 2196469Dutch.