1. Adolescent Health Unit, Second Department of Pediatrics, National and Kapodistrian University of Athens, Athens, Greece.
2. IVO Addiction Research Institute, Rotterdam, The Netherlands.
3. Erasmus University Medical Center, Rotterdam, The Netherlands.
4. University of Akureyri, Akureyri, Iceland.
5. Nobody's Children Foundation, Warsaw, Poland.
6. Grigore T. Popa University of Medicine and Pharmacy, Iasi, Romania.
7. Panteion University of Social and Political Sciences, Athens, Greece.