%0 Journal Article %T Hardcore Adolescent Smokers? An Examination of the Hardening Hypothesis by Using Survey Data From Two Norwegian Samples Collected Eight Years Apart %A von Soest, Tilmann %A Pedersen, Willy %J Nicotine and Tobacco Research %V 16 %N 9 %P 1232-1239 %@ 1462-2203 %D 2014-09-11 %I Oxford University Press %~ DeepDyve