2008 Behrman article: Luck of the draw: common adulterants found in illicit drugs.
Erowid
Earth
E
D004340:Drug Contamination; D006801:Humans; D013287:Illicit Drugs / Q000009:adverse effects / Q000737:chemistry*; D007649:Ketamine / Q000009:adverse effects / Q000032:analysis*; D018817:N-Methyl-3,4-methylenedioxyamphetamine / Q000032:analysis*; D011933:Reagent Kits, Diagnostic
D013287:Illicit Drugs; D011933:Reagent Kits, Diagnostic; D007649:Ketamine; D018817:N-Methyl-3,4-methylenedioxyamphetamine