%0 Generic %D 1999 %T Estimating the uptake of traffic-derived NO2 from N-15 abundance in Norway spruce needles %A Ammann, M. %A Siegwolf, R. %A Pichlmayer, F. %A Suter, M. %A Saure, M. %A Brunold, C. %B Oecologia %V 118(2) %P 124-131