Exclusive Pay per puff? Caffeine stick? E cigarette boom sparks race for new patents Reuters Carcinogens found in regular cigarettes are in e cigarettes, too, study finds The Washington Post E cigarettes Stress Lungs, Impair Protein Function News Release PNNL E cigarettes Stress Lungs, Impair Protein Function News Release PNNL Harvard scientist finds microbial contaminants in e cigs Harvard Gazette E cigarettes with cigarette like nicotine delivery reduce exposure to carcinogen Penn State University