[en] The energies of a few γ-rays from 23 to 125 keV from the decay of the radioisotopes ¹⁶¹Tb, ¹⁷²Hf+¹⁷²Lu, and ²⁴¹Am have been determined. These energies were obtained from measurements of differences in the energies of closely spaced lines. The statistical components of the uncertainties of these energy differences range from 0.1 to 1.9 eV. Since it is a long-lived nuclide, these results should make ¹⁷²Hf, which has γ-rays from 23 to 125 keV, a useful energy calibration source. For ²⁴¹Am, our value of 59.5412(2) for this widely used line differs from the previously accepted value of 59.537(1) keV. (orig.)