Britt (DiBenedetti) DM, Collins FL, Cohen LM. Cigarette smoking and chewing gum use among college students. J Appl Biobehav Res. 2007 Jun 4;4(2):85-90. doi: 10.1111/j.1751-9861.1999.tb00057.x
Anderson JJB, Anthony M, Messina M, Garner SC. Effects of phyto-oestrogens on tissues. Nutr Res Rev. 1999 Jun;12(01):75-116.