RT Article T1 Two decades of change in premarital first births: Cohort comparisons from the NLSY79 and NLSY97 A1 Wu, Lawrence L. 1958- A2 Kaufman, Pamela A2 Martin, Steven P. LA English PB Bureau of Labor Statistics Conference Center YR 2008 UL https://krimdok.uni-tuebingen.de/Record/191273138X K1 Konferenzschrift ; 2008 ; Washington, D.C