Belgian national report on drugs 2011, new developments, trends and in-depth information on selected issues, Deprez, N, Antoine Jérôme, Asueta-Lorente J.F., Bollaerts K., Van der Linden T, and Van Bussel Johan , 0/0/2012, Volume D/2012/2505/08, Number 358, Brussels, p.358, (2012)