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3. Explaining female teenagers' sexual behavior and outcomes: A bivariate probit analysis with selectivity correction;Afexentiou;Journal of Family and Economic Issues,1997
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5. Alan Guttmacher Institute (2006). U.S. teenage pregnancy statistics: Overall trends, trends by race and ethnicity and state-by-state information. Retrieved April 17, 2009 from www.guttmacher.org/pus/state-pregnancy-trends.pdf