We say we will never forget, but it is the responsibility of each generation to hold true to that oath. Some of these are history books. Others are fiction. But all are worth your time. Although most of the books on this list focus on the Holocaust itself, centrality to the Nazi ideology of systematically wiping any trace of the Jewish people from the planet, there were other victims. (Numbers below are estimates)
Jewish victims of the Holocaust - 6,000,000
Other Nazi genocide victims -
Non-Jewish Polish civilians - 1,800,000
Roma & Sinti - 500,000
Disabled civilians (mostly German) - 250,000
Homosexuals - 6,000
And these are only estimates of the numbers in Europe. Japanese massacres in Asia produced at least a similar number of noncombatant deaths. If not more - possibly up to 19 million. Nothing as systematic as the Holocaust, but every bit as horrific.