Titman, Wendy. Special Places; Special People: The Hidden Curriculum of School Grounds. Surrey, England: World Wide Fund for Nature/Learning through Landscapes; New York: Touchstone, 1994.
United Nations.The Convention on the Rights of the Child. New York: UNICEF, 1989.
U.S. Fish and Wildlife Service. «Directory of Schoolyard Habitats Programs». Annapolis, MD: U.S. Fish and Wildlife, 1996.
Wadsworth, Ginger. Rachel Carson: Voice for the Earth. Minneapolis: Lerner Publications, 1992.
Wagner, Cheryl. Planning School Grounds for Outdoor Learning. Washington, D.C.: National Clearinghouse for Educational Facilities, 2000.
Westland, C., andj. Knight. Playing, Living, Learning: A Worldwide Perspective on Children's Opportunities to Play. State College, Pennsylvania: Venture Publishing, 1982.
Wilson, Edward O. Biophilia. Cambridge, MA: Harvard University Press, 1986.