Kostyantyn Nasyedkin, Masamitsu Watanabe, and Kimitoshi Kono, Anomalous temperature dependence of energy levels of electrons on helium, Low Temp. Phys. 49, 955–960, (2023) [Fiz. Nyzk. Temp. 49, 1050–1055, (2023)] DOI: https://doi.org/10.1063/10.0020162.