  We consider RKKY interaction between two magnetic impurities in graphene. The
consideration is based on the perturbation theory for the thermodynamic
potential in the imaginary time representation. We analyze the symmetry of the
RKKY interaction on the bipartite lattice at half filling. Our analytical
calculation of the interaction is based on direct evaluation of real space spin
susceptibility. We show in the Appendix, added to the published version, that
the approach can be easily generalized to the case of finite temperature.
