@article {547,
	title = {Differential effects of ammonium nitrate on three heathland species},
	volume = {135},
	year = {1998},
	pages = {185-196},
	author = {De Graaf, M.C.C. and Bobbink, R. and Roelofs, J.G.M. and Verbank, P.J.M.}
}
