An approximate global solution to the gravitational field of a perfect   fluid in slow rotation
  Using the Post-Minkowskian formalism and considering rotation as a perturbation, we compute an approximate interior solution for a stationary perfect fluid with constant density and axial symmetry. A suitable change of coordinates allows this metric to be matched to the exterior metric to a particle with a pole-dipole-quadrupole structure, relating the parameters of both. 
J. A. Cabezas and E. Ruiz