1. See the survey by G. J. Stigler, “Perfect Competition, Historically Contemplated,” inEssays in the History of Economics (Chicago, 1965).
2. See Charles M. Tiebout, “A Pure Theory of Local Expenditures,”Journal of Political Economy, October 1956.
3. This first condition is generally invoked. See A. Ranney and W. Kendall, “The American Party System”,American Political Science Review, June 1954, for references to the later literature, see D. G. Pfeiffer, “The Measurement of Inter-Party Competition and Systematic Stability”,American Political Science Review, June 1957, and R. I. Hofferbert, “Classification of American Party Systems”,Journal of Politics, August 1964.
4. See J. Schlesinger, “A Two-Dimensional Scheme of American Party Systems”,American Political Science Review, 1955.
5. See H. Hotelling, “Stability in Competition,” reprinted inReadings in Price Theory (edited by G. Stigler and K. Boulding); also A. Smithies, “Optimum Location in Spatial Competition,”Journal of Political Economy, June 1941.