Mattogno, his Einsatzgruppen book and the Gas Vans
In mid-May 1943, the German Foreign office was troubled by a story that the Generalkommissar for Weissruthenien, Wilhelm Kube, showed an Italian delegation of fascists "a gas chamber in which the killing of the Jews was allegedly carried out" in Minsk (see 1943-05-15 Opera and Gas-Chamber: Italian Fascist Delegation’s Visit to Nazi-Occupied Minsk). This was a mobile "gas chamber", since only gas vans are known to have operated in Minsk (see also here).