Play, Naturally: A Review of Children's Natural Play

http://www.playengland.org.uk/resources/play,-naturally-a-review-of-children's-natural-play.aspx

You can download the entire review from the link above. "The review, Play, naturally: A review of children's natural play, looks at the benefits of play on children's health and well-being, and outlines what we should be doing to compensate for the loss of natural play space in recent years."