TY - JOUR T1 - A stepped care strategy using buprenorphine and methadone versus conventional methadone maintenance in heroin dependence: a randomized controlled trial JF - Am J Psychiatry Y1 - 2007 A1 - Kakko, J A1 - Gronbladh, L A1 - Svanborg, KD A1 - et, al VL - 164 SP - 797-803 IS - 5 ER -