Study Shows Effects of Prenatal Exposure to Secondhand Smoke Greater for Socioeconomically Disadvantaged Children (National Institute of Environmental Health Sciences) - http://www.nih.gov/news/pr/mar2004/niehs-15.htm
State-Specific Prevalence of Cigarette Smoking among Adults, and Policies and Attitudes about Secondhand Smoke--U.S., 2000 (Centers for Disease Control and Prevention) - http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5049a1.htm