@book{20159,
	author = {Heck, William Harry,},
	title = {A study of school recesses.},
	publisher = {The University},
	year = {[1917]},
	series = {University of Virginia record.  Extension ser.,},
	address = {[Charlottesville, Va.]},
	url = {http://hdl.loc.gov/loc.gdc/scd0001.0021496983A}
}