A. P. Allen and A. P. Smith, “Effects of Chewing Gum and Time-on-Task on Alertness and Attention,” Nutritional Neuroscience 15, no. 4 (July 2012): 176–85, doi: 10.1179 /1476830512Y.0000000009; C. Lee, “How Chewing Gum Can Boost Your Brain Power,” DailyMail.com, April 1, 2013, http://www.dailymail.co.uk/health/article-2302615/How-chewing-gum-boost-brain-power.html.
