Cohen LM, Britt DM, Collins FL, Al'Absi M, McChargue DE. Multimodal assessment of the effect of chewing gum on nicotine withdrawal. Addict Behav. 2001 Mar 1;26(2):289-95.
Mansfield CA. A consistent method for calibrating contingent value survey data. South Econ J. 1998;64(3):665-81.
Cohen LM, Collins FL, Britt DM. The effect of chewing gum on tobacco withdrawal. Addict Behav. 1997 Nov 1;22(6):769-73.