Grib, A., R. Vovk, and V. Shaternik. “Coherent Emission from a Stack of Long Josephson Junctions Based on Low-Temperature Superconductors”. Journal of V. N. Karazin Kharkiv National University. Series Physics, no. 26, Jan. 2018, pp. 28-32, https://periodicals.karazin.ua/physics/article/view/10079.