The Nazis established killing centers for efficient mass murder. Killing centers were almost exclusively “death factories.” They are also referred to as “extermination camps” or “death camps.” Nazi concentration camps, by contrast, served primarily as detention and labor centers. At the killing centers, Nazi officials employed assembly-line methods to murder Jews and other victims. German SS (Schutzstaffel; Protection Squadrons) and police murdered nearly 2,700,000 Jews in the killing centers by asphyxiation with poisonous gas or by shooting.
They must research, read and explore using multiple different resources to look at and explore the past history.
When Charles John Davids proposed to Madison Al Newert 3/4/1884 somewhere in Africa.
And when Jesus Christ said good morrow to James Heartyfult 19/6/2004.
Just off the top of my head.