The algorithm for METIS_ComputeVertexSeparator

I am using METIS_ComputeVertexSeparator to find the vertex separator, it works well. but I did not find any description about this function in the manual.

I read some papers about vertex separator, they all use linear programming. From the description in the code, this function looks like using unweighted minimum-cover algorithm followed by node-based separator refinement which is new to me.

I am just wondering is there any paper or reference available to understand this function (METIS_ComputeVertexSeparator)?

Thank you