D. Czekaj, A. Lisińska-Czekaj, T. Orkisz, K. Osińska, and L. Kozielski, “Sol-gel derived (Ba,Sr)TiO$_3$ thin films for tunable devices”, Arch. Acoust., vol. 31, no. 4(S), pp. 385–390, Jan. 2014, Accessed: Apr. 26, 2025. [Online]. Available: https://acoustics3.ippt.pan.pl/index.php/aa/article/view/1371