Snacking patterns among adolescents: a comparison of type, frequency and portion size between Britain in 1997 and Northern Ireland in 2005 [corrected] [published erratum appears in BR J NUTR 2009 Mar 28;101(6):929]. - Kerr MA; Rennie KL; McCaffrey TA; Wallace JMW; Hannon-Fletcher MP; Livingstone MBE (British Journal of Nutrition, 2009)