1. Boolos, G. 1996. ‘On the proof of Frege's theorem’, in A. Morton and S. P. Stich (eds.), Benacerraf and His Critics, New York: Basil Blackwell, pp. 143–159.
2. Chateaubriand, O. 2003. ‘How is it determined that that true is not the same as the false’, in M. Ruffino (ed.), Logic, Truth and Arithmetic: Essays on Gottlob Frege, Manuscrito, Volume 26, pp. 347–357.
3. Cook, R. 2019. ‘Frege's Little Theorem and Frege's Way Out’, in P. Ebert & M. Rossberg (eds.), Essays on Frege's Basic Laws of Arithmetic, Oxford: Oxford University Press, pp. 384–410.
4. Duarte, B. A. 2009. Lógica e Aritmética na Filosofia da Matemática de Frege, Ph.D. Dissertation Pontífica Universidade Cathólica, Rio De Janeiro.
5. Frege, G. 1874. ‘Methods of calculation based on an extension of the concept of quality’, in B. McGuinness (ed.), Gottlob Frege: Collected Papers on Mathematics, Logic and Philosophy, New York: Basil Blackwell, pp. 56–92. This was Frege's dissertation for the Venia docendi in the Philosophical Faculty of Jena.