2Outdoor Industry Foundation. Outdoor Recreation Partication Report[ R]. Boulder: Outdoor Industry Foundation ,2010.
3Outdoor Industry Foundation. The Active Outdoor Recreation Economy [ R ]. Boulder: Outdoor Industry Foundation ,2006.
4Clayne Jensen, Steven Guthrie. Outdoor Recreation in America - 6th Edition[ M ]. Champaign : Human Kinetics. 2005.
5National Park Service U. S. Department of the Interior Public Use Statistics - 2006 Regional Report[ R]. 2006.
6Clayne R. Jensen, Steven Guthrie. Outdoor Recreation in America [M]. 6th. The United States; Human Kinetics, 2005: 11-13.
7Outdoor Industry Association. State of the Industry Report [R]. The United States: Outdoor Industry Association, 2006.
8Cordell H K, Betz C J, Green G T. Nature-based Outdoor Recreation Trends and Wilderness [J]. International Journal of Wilderness, 2008 (14): 7-9,13.
9Outdoor Industry Foundation. The Next Generation of Outdoor Participants[R]. The United States: Outdoor Industry Foundation, 2007.
10The Recreation Roundtable. Outdoor Recreation in America 2003: Recreation's Benefits to Society Challenged by Trends[R]. The United States,The Recreation Roundtable,2004.
