Most of the victims murdered in Sobibor were Polish Jews from the area of Lublin and from occupied parts of the Soviet Union. Figures vary about the total number of victims in Sobibor. In his book about Sobibor, Jules Schelvis - one of the few survivors of the camp - mentioned 192,000. The authoritative United States holocaust Memorial Museum states that at least 167,000 victims were murdered in Sobibor. The nazis also sent trains from Austria, Slovakia, Bohemia and Moravia, the Netherlands, and France to Sobibor. There were 19 trains that left the Dutch transit camp Westerbork to Sobibor. Of the more than 34,000 Dutch victims, less than 1,000 were not gassed immediately, but were put to work. Of these only 18 survived Sobibor. Forced labour took place in Sobibor or in one of the camps in the vicinity of Lublin. Starting in the autumn of 1942, the prisoners had to dig up the mass graves in Sobibor and burn the bodies. To conceal their atrocities as much as possible, the SS used a machine to pulverise the bones of the corpses.