As Minnesota's tobacco trial enters its final days, attorneys for the state and Blue Cross Blue Shield have introduced into evidence a final batch of formerly-secret tobacco industry documents. They include research into the smoking motivations of children, and lawyers' memos about smoking and health research. The state contends tobacco companies marketed to underage smokers, and covered up research linking smoking and disease. Minnesota Public Radio's Laura McCallum reports... The state's legal team hinted some of the most incriminating company documents would come in this last group of memos, many of them from the