Disposable e cigarettes and their nicotine delivery, usage pattern, and subjective effects in occasionally smoking adults Scientific Reports UofL study shows nicotine in e cigarettes may not be harmless, as some claim UofL News E cigarettes didn't help smokers quit, study says CNN Comparison of Nicotine Levels Between Cigarettes and Vapes Ecigator E Cigarettes: Flavored Products Fuel Campaign for Tobacco Free Kids FDA hazy on e cigarettes' safety CNN.com