"Case studies"@en . "Case studies" . . . . . . . . . . . "An epidemiologic study of heroin use patterns and trends in four cities on the Mexican-American border" . "An epidemiologic study of heroin use patterns and trends in four cities on the Mexican-American border"@en . . . . . . . "Drogas Consumo Estados Unidos." . . "HeroĆ­na." . . "Heroin Dependence epidemiology United States." . . . .