S. Altanany, I. Zajcewa, R. Minikayev, and M. Cieplak, “Berezinskii–Kosterlitz–Thouless Transition in Ultrathin Niobium Films”, Acta Phys. Pol. A, vol. 143, no. 2, p. 129, Feb. 2023, doi: 10.12693/APhysPolA.143.129.