1. Smith JC. Abortion surveillance report, hospital abortions, annual summary 1969. Atlanta, GA: US Department of Health, Education, and Welfare, Public Health Service, Health Services and Mental Health Administration, National Communicable Disease Center; 1970.
2. Abortion surveillance—United States, 2005.;Gamble;MMWR Surveill Summ,2008
3. Henshaw SK, Kost K. Trends in the characteristics of women obtaining abortions, 1974 to 2004. New York, NY: Guttmacher Institute; 2008. https://www.guttmacher.org/pubs/2008/09/23/TrendsWomenAbortions-wTables.pdf
4. Trends in abortion in the United States.;Jones;Clin Obstet Gynecol,2009
5. Abortion surveillance—United States, 2006.;Pazol;MMWR Surveill Summ,2009