In the ERIC database,
EJ indicates the item is a journal article.
ED indicates the item is an ERIC document:Which includes... research reports, conference papers, issue papers, monographs, and ERIC digests. ERIC indexes education-related materials from a variety of sources, including scholarly organizations, professional associations, research centers, policy organizations, university presses, the U.S. Department of Education and other federal agencies, and state and local agencies. Individual contributors submit conference papers, research papers, dissertations, and theses.
From 1966-2004 many of these ED documents were made available on microfiche; the a large portion of the microfiche set is available at the Pepperdine West L.A. campus and is available through Pepperdine Campus Loan (ask at the Research Help or Check Out desk).