Search Results Use the search box below to revise your search, or start a new search. Studies (3) Variables Publications Your query returned 2 studies. Series results are grouped under the most relevant study. Ungroup series results to view all results. Sort by: Title A-Z Released/Updated Time Period Most Cited in ICPSR Bib. 1. Great Plains Population and Environment Data: Agricultural Data, 1870-1997 [United States] (ICPSR 4254) Gutmann, Myron P. 1 more result in Great Plains Population and Environment Data Series 2. White Attitudes Toward Black Civil Equality in the Nineteenth Century: Iowa's Equal Rights Referenda of 1857, 1868, and 1880 (ICPSR 4284) Dykstra, Robert R.