Research on post-1959 Cuba has been handicapped because scholars in the country have concentrated on the years before 1959 and because field research in Cuba by outsiders on the post-1959 period has been rare and difficult. The secondary literature relies heavily on three types of sources: research on publications issued by the Cuban government, impressions of scholarly and other visitors to Cuba based on varying levels of systematic observation and research, and research on Cuban exiles. The last of these, however, focusses mostly on the exiles’ integration into the United States rather than on generating systematic information about Cuba itself. The main scholarly journal for the study of contemporary Cuba is Cuban Studies, edited from 1970 to 1990 by Carmelo Mesa-Lago at the Center for Latin American Studies, University of Pittsburgh. Published twice a year until 1985, and once a year thereafter, it features scholarly articles principally, though not exclusively, by social scientists on post-1959 Cuba. Each issue also carries the best and most complete bibliography of research on Cuba, conducted in or outside Cuba, in all fields. See also Ronald H. Chilcote and Cheryl Lutjens (eds.), Cuba: 1953–1978: A Bibliographic Guide to the Literature, 2 vols. (White Plains, N.Y., 1986), and Louis A. Perez, Jr., Cuba: An Annotated Bibliography (Westport, Conn., 1988). For bibliography on the years before 1970, see Nelson P. Valdés and Edwin Lieuwen, The Cuban Revolution: A Research-Study Guide (1959–1969) (Albuquerque, N.Mex., 1971). The best cartographic work is the joint publication by the Academia de Ciencias de Cuba and the Academia de Ciencias de la URSS, Atlas nacional de Cuba (Havana, 1970).