With the notable exceptions of Raul Hilberg who put the number of Jewish deaths at 5,100,000 and Gerald Reitlinger who proposed low and high estimates (4,204,400 to 4,575,400 victims) most authors concur that about 6,000,000 Jews were murdered in World War II, the majority of them with poison gas in death camps or by mobile shooting units.
The specialists of the Holocaust have generally reached their counts on a per-country basis, which poses a problem since, from 1938 onwards and after the end of the war, Europe was subject to many border changes. The number of victims advanced often comes of subtracting the number of survivors in various countries after 1945 from their prewar populations. The literature is thus full of double counts of victims between the USSR and Poland, and also between Hungary, Romania and Slovakia. Reliable sources giving precise vital statistics on European countries and correct Jewish immigration and refugee figures for the 1930s and during the war, notably into Africa, Asia and Latin America, are yet available. Official sources in German, Spanish, Portuguese, Italian, French, Polish, Romanian, Hungarian and Russian abound, allowing for rectifications of blatant gaps in the historiography of the Holocaust.
Making use of many sources in several languages and studying thoroughly the death tolls of death camps, shooting units or attrition in ghettos, the author has been able to find that the number of Jewish victims was very close to Gerald Reitlinger’s high estimate, proving the latter author to have been, in this respect, the most accurate Holocaust scholar.