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
Reed (Earnshaw) SR, Reed JH, Stuhldreher TJ. Transaction costs, taxes, and portfolio revision. J Contemp Bus Issue. 1997;5:40-8.