“ A study on the stability of anhydroecgonine methyl ester (crack biomarker), benzoylecgonine, and cocaine in human urine ”, Arch Clin Psychiatry (former: Rev Psiq Clin), vol. 35, no. supl.1, pp. 17–20, Jan. 2008, doi: 10.1590/S0101-60832008000700005.