@article {1276,
	title = {Physiological effects of long term exposure to low concentrations of SO2 and NH3 on poplar leaves.},
	journal = {Plant Physiology},
	volume = {82},
	year = {1991},
	pages = {32-40},
	author = {van Hove, L.W.A. and van Kooten, O. and van Wijk, K.J and Vredenberg, W.J. and Adema, E.H. and Pieters,  G.A.}
}
@article {1640,
	title = {Physiological effects of long term exposure to low concentrations of SO2 and NH3 on poplar leaves.},
	journal = { Physiologia Plantarum},
	volume = {82},
	year = {1991},
	pages = {32-40},
	author = {van Hove, L.W.A. and van Kooten, O. and van Wijk, K.J and Vrendenberg, W.J. and Adema, E.H. and Pieters, G.A.}
}
