51. Polity V: Political Regime Characteristics and Transitions, 1800-2018 Bookmark Format Series - ongoing
52. Population Exposure Estimates in Proximity to Nuclear Power Plants, Locations (1956-2012) Bookmark Format Series - ongoing
58. Third International Mathematics and Science Study: International Curriculum Analysis, 1992-1995 (TIMSS) Bookmark Format Series - ongoing
59. Trends in International Mathematics and Science Study (TIMSS) (1995+) Bookmark Format Series - ongoing