research Incorporation of Isotopically Labeled Cocaine and Metabolites into Human Hair: 1. Dose-Response Relationships 128 citations , January 1996 in “Journal of analytical toxicology.” Hair analysis can detect cocaine use but doesn't accurately show the amount or timing of use.
research Influence of thermal hair straightening on cannabis and cocaine content in hair 23 citations , January 2016 in “Forensic Science International” Thermal hair straightening changes drug levels in hair, affecting test results.