sentences:  The widely known phrase "Auschwitz lie" (German "Auschwitzlüge") can be traced to Christophersen, whose 1973 book of that name disputed the existence of gas chambers at the Auschwitz concentration camp.Along with Christophersen's own writings, that book also contains further contributions and forewords from other Holocaust deniers, including the former lawyer and convicted violent criminal Manfred Roeder (classified as a terrorist in Germany) and the former judge Wilhelm Stäglich.Since 1993 the book has been included on a list of materials that may not be distributed to young people, as ruled by Germany's Federal Department for Media Harmful to Young Persons, due to its Holocaust-denying content.