4Breslau N, Peterson EL. Smoking cessation in young adults: age at ini- tiation of cigarette smoking and other suspected influences[J 1. Ameri- can Journal of Public Health, 1996,86(2) :214 220.
5Tessier JF, Freour P, Belougne D, et al. smoking habits and attitudes of medicall students towards smoking and anti - smoking campaigns in nine Asiaan countries[J]. Int J Epidemiol, 1992,21 (2) :298 - 304.