1. a Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Division of Adolescent and School Health , 4770 Buford Hwy, NE Mailstop K-12, Atlanta , GA , 30341-3717 , USA
2. b Centers for Disease Control and Prevention, National Center for Injury Prevention and Control, Division of Unintentional Injury Prevention
3. c Centers for Disease Control and Prevention, National Center for Injury Prevention and Control, Division of Violence Prevention