Generalizing the flux formula (231) to point masses moving on quasi elliptic orbits dates back to the work of Peters and
Mathews [178] at Newtonian order. The result was obtained in [217, 49] at 1PN order, and then further extended by
Gopakumar and Iyer [122] up to 2PN order using an explicit quasi-Keplerian representation of the motion [99, 197]. No
complete result at 3PN order is yet available.