Maintenance work on the ZORA database servers is scheduled for Thursday 25th July 2019 from 19:00-20:00. During this period ZORA and JDB will not be available. Thank you for your understanding.
Boumparis, N; Karyotaki, E; Schaub, Michael P; Cuijpers, P; Riper, Heleen (2017). Internet interventions for adult illicit substance users: a meta-analysis. Addiction, 112(9):1521-1532.