Just for reference (in the sense of physics meaning of reference) - and
There’s no excuse for the kind of violence that we saw yesterday. It is counterproductive,” Obama said at a press conference from the White House. “When individuals get crowbars and start prying open doors to loot, they’re not protesting. They’re not making a statement. They’re stealing. When they burn down a building, they’re committing arson. And they’re destroying and undermining businesses and opportunities in their own communities. That robs jobs and opportunity from people in that area.”