The Holocaust was carried out in many different countires and information about it exists in many languages, chiefly German, Yiddish, Polish, Hebrew, and Russian. Please be aware of variances in spelling when translerating from non-Roman alphabets. Further, the names the names of some towns were germanized to make it easier for them. The Polish name of the town was Oświęcim, but it is best known by the German name, Auschwitz.
You may want to consult works on the history of individual countries as background for understanding the economic and political situation prior to the war.