Between then and now, the amount of material has grown in...

Between then and now, the amount of material has grown in huge measure. This is a huge amount of documentation, none of which has been seriously researched before. What's really being talked about is the massive potential addition to what we know and what we are able to learn, not just the way individuals were treated, but about the concentration camp system, how forced and slave labor worked, about the experiences of people who survived.