You may not know the name Jim Marshall, but you almost certainly know his photographs. His collection of work is a near-complete account of the cultural revolution that took place in the late 1960's, from jazz clubs to Woodstock. And while Marshall was both notably talented and difficult to work with, few photographers have covered as much ground as Marshall did. Now, his long-time assistant, Amelia Davis, is trying to promote Marshall's work, and alter the way the world thinks about the legendary photographer. NewsHour Weekend's Christopher Booker has the story.