Search Results Use the search box below to revise your search, or start a new search. Studies (1) Variables Publications Your query returned 1 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. National Study of Law Enforcement Agencies' Policies Regarding Missing Children and Homeless Youth, 1986 (ICPSR 6127) Collins, James J.,; McCalla, Mary Ellen; Powers, Linda L.; et al.