AMSTERDAM (AP) — Health authorities in Amsterdam are warning of dangerous drugs being sold to tourists after three British men died in the last month after snorting heroin they may have believed was cocaine. A large sign outside the Dutch capital's Central Station warned Thursday, "Extremely dangerous cocaine is sold to tourists" in the area. The warning campaign was started after two British men, aged 20 and 21, were found dead in a hotel room in the city on Tuesday.Read more on NewsOK.com