V. A. Maidanov, V. E. Syvokon, and S. S. Sokolov, Analysis of experiments on the study of electrical activity in helium, Low Temp. Phys. 48, (2021) [Fiz. Nyzk. Temp. 48, 143-153, (2021)] DOI: https://doi.org/10.1063/10.0009292.