1. Michał Eckstein, Nicolas Franco
Causal structure for noncommutative geometry
Frontiers of Fundamental Physics, vol. 14, pp. 138-xxx (2015).

2. Nicolas Franco, Michał Eckstein
Noncommutative geometry, Lorentzian structures and causality
in “Mathematical Structures of the Universe”, eds. M. Eckstein, M. Heller, S.J. Szybka, Copernicus Center Press (2014), pp. 315-340

3. Nicolas Franco
Towards a noncommutative version of Gravitation
AIP Conference Proceedings, vol. 1241, pp. 588-594 (2010).

4. Nicolas Franco
Survey of Gravity in Non-Commutative Geometry
Topology, Quantum fields theory & Cosmology, Hermann, pp. 313-329 (2009).