1. Addiction Research Methods Institute, World Federation for the Treatment of Opioid Dependence, 225 Varick Street, Suite 402, New York, NY 10014, USA
2. Department of Psychiatry and Addictions, Section of Psychiatry, North-Western Tuscany Local Health Unit, Tuscany NHS, Versilia Zone, Via Aurelia 335, 55041 Viareggio, Italy
3. V.P. Dole Research Group, G. De Lisio Institute of Behavioural Sciences, Via di Pratale 3, 56121 Pisa, Italy
4. Department of Psychiatry and Addictions, Section of Addictions, North-Western Tuscany Local Health Unit, Tuscany NHS, Pisa Zone, Via delle Torri 160, 56124 Pisa, Italy
5. Department of Mental Health and Addictions, Division of Psychiatry, ASST Crema, Via Largo Dossena 2, 26013 Crema, Italy
6. Department of Clinical and Experimental Medicine, University of Pisa, Via Roma 67, 56100 Pisa, Italy
7. Saint Camillus International University of Health Sciences (UniCamillus), Via di Sant’Alessandro 8, 00131 Rome, Italy