Patricia Cristina Venturini, Nelson Studart, and José Pedro Rino, Dynamical structure factor of two-dimensional electrons over a helium film: Электроны над жидким гелием, Low Temp. Phys. 34, (2008) [Fiz. Nizk. Temp. 34, 484-488, (2008)] DOI: https://doi.org/10.1063/1.2911661.