TY - JOUR AN - 13 AU - Thapar,A. AU - Harrington,R. AU - McGuffin,P. TI - Examining the comorbidity of ADHD-related problems using a twin study design. JO - Br J Psychiatry PY - 2001 VL - 179 SP - 224-229 M2 - 224 DO - 10.1192/bjp.179.3.224 ER -