http://www.voanews.com/mediaassets/specialenglish/2009_10/Audio/Mp3/se-hea-behavior-studies-21oct09_0.Mp3 Punishment or Reward: Which Works Better on Behavior? http://www.manythings.org/voa/scripts/2009-10/VOA_Special_English_2009-10-20_-_Punishment_or_Reward_-_Which_Works_Better_on_Behavior.html 2009-10-20 http://www.voanews.com/voanews_shared/images/widgetBarIcon.png