1. Almond, G.A. (1956). “Comparing Political Systems”, Journal of Politics, 17, 391–409.
2. Blondel, J. (1968). “Party Systems and Patterns of Government in Western Democracies”, Canadian Journal of Political Science 1, 180–203.
3. Butler, D. and A. Ranney (eds)(1978). Referendum: A Comparative Study of Practice and Theory. Washington: American Enterprise Institute.
4. Daalder, H. (1971). “Cabinets and Party Systems in Ten Smaller European Democracies”, Acta Politica, 6, 282–303.
5. Dodd, L.C. (1976). Coalitions in Parliamentary Government. Princeton: Princeton U.P.