1. Boolos, G., "Saving Frege from contradiction," Proceedings of the Aristotelian Society, vol. 87 (1986), pp. 137-51
2. reprinted on pp. 438-52 in Frege's Philosophy of Mathematics, edited by W. Demopoulos, Harvard University Press, Cambridge, 1995. Zbl 0900.03021 MR 1376407
3. Boolos, G., "The consistency of Frege's Foundations of Arithmetic," pp. 3-20, in On Being and Saying: Essays in Honor of Richard Cartwright, edited by J. J. Thompson, The MIT Press, Cambridge, 1987
4. reprinted on pp. 211-33 in Frege's Philosophy of Mathematics, edited by W. Demopoulos, Harvard University Press, Cambridge, 1995. Zbl 0900.03062 MR 1376397
5. Boolos, G.. "The standard of equality of numbers," pp. 261-77 in Meaning and Method: Essays in Honor of Hilary Putnam, edited by G. Boolos, Cambridge University Press, Cambridge, 1990