, 2017, Mathematical truth revisited: mathematics as a toolbox, in E. Agazzi (ed.), Varieties of scientific realism, Dordrecht, Springer, pp. 395-406.
, 2015a, Sets, truth, and recursion, in T. Achourioti, H. Galinon, J. Martínez Fernández & K. Fujimoto (eds.), Unifying the philosophy of truth, Dordrecht, Springer, pp. 143-152.
, 2015b, 'What is a proof?', Axiomathes 25 (1), 79-91.
with Alama, J. , 2013, Computing with mathematical arguments, in H. Andersen, D. Dieks, T. Uebel, W. J. González & G. Wheeler (eds.), New challenges to philosophy of science, Dordrecht, Springer, pp. 9-22.
, 2006, 'A proof-theoretic view of necessity', Synthese 148 (3), 659-673.
with Schroeder-Heister, P. , 2006, 'Introduction: proof-theoretic semantics', Synthese 148 (3), 503-506.
with Buldt, B. , Halbach, V. , 2005, 'Reflections on Frege and Hilbert', Synthese 147 (1), 1-2.
, 2002a, 'Mathematical proof theory in the light of ordinal analysis', Synthese 133 (1-2), 237-255.