CronBerg data frame has 18 rows and 5 variablesdata(CronBerg)GNPURBLITINDUSDEMOCLipset, Seymour M. (1963) Political Man. The Social Bases of Politics. Doubleday: New York.
Schneider, C. Q., Wagemann, C. (2012) Set-Theoretic Methods for the Social Sciences, Cambridge University Press: Cambridge.
Schneider, C. Q., Wagemann, C., Quaranta, M. (2012) How To... Use Software for Set-Theoretic Analysis. Online Appendix to "Set-Theoretic Methods for the Social Sciences". Available at www.cambridge.org/schneider-wagemann