In 1991, Holocaust deniers Robert Faurisson and Siegfried Verbeke produced a booklet titled "The Diary of Anne Frank: A Critical Approach", in which they revived the allegation that Otto Frank wrote the diary. Purported evidence, as before, included several contradictions in the diary, that the prose style and handwriting were not those of a teenager, and that hiding in the "Achterhuis" would have been impossible. In 1993, the Anne Frank House in Amsterdam and the Anne Frank Fonds in Basel filed a civil lawsuit to prohibit further distribution of Faurisson and Verbeke's booklet in the Netherlands. In 1998, the Amsterdam District Court ruled in favour of the claimants, forbade any further denial of the authenticity of the diary and unsolicited distribution of publications to that effect, and imposed a penalty of 25,000 guilders per infringement.