Friendship groups and physical activity: qualitative findings on how physical activity is initiated and maintained among 10–11 year old children
Russell Jago, Rowan Brockman, Kenneth R Fox, Kim Cartwright, Angie S Page, and Janice L Thompson
Int J Behav Nutr Phys Act. 2009; 6: 4. Published online 2009 January 12. doi: 10.1186/1479-5868-6-4.PMCID: PMC2631002