On the regularization of the Kepler problem
On the Robinson theorem and shearfree geodesic null congruences
On the spherical symmetry of static perfect fluids in general relativity
On the spherical symmetry of static stellar models
On the stability of the scalar field in the gravitational field of a rotating (Kerr-) black hole
On the stability of the Taub universe
On the structure of space-time caustics
On the topology of black holes
On the total electric charge and mass of an elliptic universe
On the uniqueness of static perfect-fluid solutions in general relativity
On the universality of linear Lagrangians for gravitational field.
On theories of gravitation with nonsymmetric connection.
On two-dimensional supergravity and the quantum super-Möbius group
On Uncertainty Relations and States in Deformation Quantization
Operator representation of gravitational constraints in the case of a closed universe
Orbital period of a satellite of a planet in the relativistic theory of gravitation and in general relativity and the possibility of experimental verification of delay due to gravitational interaction
Orbits in a Magnetic Universe
Orthogonal transitivity, invertibility and null geodesic separability in type D vacuum solutions of Einstein's field equations with cosmological constant
Oscillating universe in the case p≠0
Painless nonorthogonal expansions