The hardest thing is the habit: a qualitative investigation of adolescent smokers' experience of nicotine dependence.
O'Loughlin J, Kishchuk N, DiFranza J, Tremblay M, Paradis G. The hardest thing is the habit: a qualitative investigation of adolescent smokers' experience of nicotine dependence. Nicotine Tob Res. 2002 May; 4(2):201-9.