Relativistic Bethe logarithm for triplet states of helium-like ions Vladimir A. Yerokhin, Vojtěch Patkóš and Krzysztof Pachucki Eur. Phys. J. D, 76 8 (2022) 142 Published online: 15 August 2022 DOI: 10.1140/epjd/s10053-022-00474-8