RT Journal Article SR Electronic T1 Cell phone use and behavioural problems: indications of unobserved heterogeneity in Divan et al's study JF Journal of Epidemiology and Community Health JO J Epidemiol Community Health FD BMJ Publishing Group Ltd SP 465 OP 465 DO 10.1136/jech.2010.131979 VO 65 IS 5 A1 Aarstad, Jarle YR 2011 UL http://jech.bmj.com/content/65/5/465.1.abstract AB