1. G. Boole, The Mathematical Analysis of Logic (Macmillan & Co., Cambridge, 1847)
2. G. Boole, An Investigation of the Laws of Thought (Macmillan & Co., Cambridge, 1854)
3. A. Cantini, I fondamenti della matematica da Dedekind a Tarski (Loescher, Torino, 1979)
4. E. Casari, La filosofia della matematica del ‘900 (Sansoni, Firenze, 1973)
5. G. Frege, Über formale Theorien der Arithmetik (1885), in G. Frege, Kleine Schriften, ed. by I. Angelelli (Olms, Hildesheim, 1990), pp. 103–111