PDF) Factors Associated with Indoor Smoking at Home: A Focus on Socioeconomic Status in South Korea E cigarettes and Smoking: Correlation, Causation, and Selection Bias Request PDF S. Korea's cigarette sales fall for second consecutive year < Economy < KEconomy < The Korea Post China bolsters e cigarette regulations to smoke out non compliance South China Morning Post 2FIRSTS South Korea Imposes Age Verification for E Cigarette Sales, Fines Up to $14,000