Feynman integrals for binary systems of black holes

The initial phase of the inspiral process a binary black-hole system can be described by perturbation theory. At third post-Minkowskian order two-loop double box graph, known as H-graph, contributes. In this talk we report how all master integrals H-graph with equal masses expressed up to weight four in terms multiple polylogarithms. We also discuss techniques for unequal mass case. essential complication (and focus talk) is occurrence several square roots.