L. OPILSKA, A. OPILSKI, and Z. LATACZ, “Relation between the energy. Gap and ultrasonic wave propagation velocities in semiconductors”, Arch. Acoust., vol. 5, no. 1, pp. 81–90, Mar. 2016, Accessed: Jun. 22, 2025. [Online]. Available: https://acoustics.ippt.pan.pl/index.php/aa/article/view/3329