1. Nicolas Franco, Michał Eckstein
Causality in noncommutative two-sheeted space-times
, vol. xxx, pp. xxx-xxx (2015).

2. Nicolas Franco, Michał Eckstein
Exploring the Causal Structures of Almost Commutative Geometries
SIGMA, vol. 10, 010 (2014).

3. Nicolas Franco, Michał Eckstein
An algebraic formulation of causality for noncommutative geometry
Class. Quantum Grav., vol. 30, p. 135007 (2013).

4. Piotr T. Chruściel, Michał Eckstein, Luc Nguyen and Sebastian J. Szybka
Existence of singularities in two-Kerr black holes
Class. Quantum Grav., vol. 28, p. 245017 (2011).

5. Piotr T. Chruściel, Michał Eckstein, Sebastian J. Szybka
On smoothness of Black Saturns
Journal of High Energy Physics, vol. 2010, pp. 1-39 (2010).