Intentionalists[who?] use the top-bottom approach to solidify their conclusion that the intent to kill the Jews was always present in the higher-ranked officials. For this idea, they point specifically to Hitler's Mein Kampf, where he, essentially, calls for the extermination of European Jews. Therefore, the idea goes that Hitler, who intended to eradicate Europe of Jews, passed down an order (physical evidence of which has never been found) to eliminate all Jews in Europe.