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
Sorensen HT, Steffensen FH, Sabroe S, Rothman KJ, Gillman MW, Fischer P. Historical cohort study of in utero exposure to uterotonic drugs and cognitive function in young adult life. West J Med. 1999 Jan 1;170(5):260-2.