van Nuijs, A.L.N.; Pecceu, B.; Theunis, L.; Dubois, N.; Charlier, C.; Jorens, P.G.; Bervoets, L.; Blust, R.; Meulemans, H.; Neels, H.; Covaci, A. (2009). Can cocaine use be evaluated through analysis of wastewater? A nation-wide approach conducted in Belgium. Addiction 104(5): 734-741. dx.doi.org/10.1111/j.1360-0443.2009.02523.x, meer