Study Search Results Your query returned 2 results. Series results are grouped under the most relevant study. You can ungroup series results. Results per page: 25 50 100 Sort by: Title A-Z Released/Updated Time Period Most Cited in ICPSR Bib. (?) Study Title/Investigator 1. Immigrants Admitted to the United States, 1972 (ICPSR 8952) United States Department of Justice. Immigration and Naturalization Service 28 more results in Immigrants Admitted to the United States Series 2. Panel Study of Income Dynamics, 1968-1999: Annual Core Data (ICPSR 7439) Hofferth, Sandra; Stafford, Frank P.; Yeung, Wei-Jun J.; et al.