"As Daniel Dennefink explains in his article on the story behind the writings of the Einstein-Rosen gravitational paper, the singularity that Einstein and Rosen had encountered was an apparent singularity introduced by their choice of coordinate system, similar to the singularity one encounters when attempting to find the longitude of the North Pole. In fact, in his referee report Robertson had indicated that the singularity was removed by a change to a cylindrical coordinate system."