1. What Numbers Could not Be
2. Brouwer, L. E. J. 1907. ‘Over de Grondslagen der Wiskunde’, PhD diss., Universiteit van Amsterdam. Translated in Brouwer 1975, pp. 13–101.
3. Brouwer, L. E. J. 1948. ‘Consciousness, philosophy, and mathematics’, in Proceedings of the 10th International Congress of Philosophy, pp. 1235–1249. Reprinted in Brouwer 1975, pp. 480–494. Amsterdam: North-Holland Publishing Company.
4. Points and Spaces