@article {609,
	title = {Effects of atmospheric ammonia and ammonium sulphate on vesicular-arbuscular mycorrhizal colonisation in three heathland species},
	volume = {127},
	year = {1994},
	pages = {685-696},
	author = {Heijine, B. and Dueck, T.A. and Van der Eerden, L.J.M. and Heil, G.}
}
