, 2000, On self-reference and self-description, in A. Carsetti (ed.), Functional models of cognition, Dordrecht, Springer, pp. 189-197.
with Calude, C. , Campbell, D. , Ştefănescu, D. , 1995, Strong determinism vs. computability, in W. Depauli Schimanovich, E. Köhler & F. Stadler (eds.), The foundational debate, Dordrecht, Springer, pp. 115-131.
, 1995, A constructivist manifesto for the physical sciences — constructive re-interpretation of physical undecidability, in W. Depauli Schimanovich, E. Köhler & F. Stadler (eds.), The foundational debate, Dordrecht, Springer, pp. 65-88.
, 1994a, Extrinsic-intrinsic concept and complementarity, in H. Atmanspacher & G. J. Dalenoort (eds.), Inside versus outside, Dordrecht, Springer, pp. 273-288.