TY - JOUR A1 - Van Heerden, A.C. A1 - Norris, S.A. A1 - Richter, L.M. T1 - Using mobile phones for adolescent research in low and middle income countries: Preliminary findings from the birth to twenty cohort, South Africa Y1 - 2010 DO - 10.1016/j.jadohealth.2009.09.008 VL - 46 IS - 3 ER -