@article {1481,
	title = {Decline of acid-sensitive plant species in heathland can be attributed to ammonium toxicity in combination with low pH.},
	volume = {166},
	year = {2005},
	pages = {551-564},
	author = {Van Den Berg, L.J. and Dorland, E. and Vergeer, P. and Hart, M.A.C. and Bobbink, R. and Roelofs, J.G.}
}
@article {1119,
	title = {Differential effects of nitrate and ammonium on three fen bryophyte species in relation to pollutant nitrogen input.},
	volume = {164},
	year = {2004},
	pages = {451-458},
	author = {Paulissen, M.P.C.P. and van der Ven, P.J.M. and Dees, A.J. and Bobbink, R.}
}
@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.}
}
