[1]
M. PAJEWSKI and M. SZALEWSKI, “Ultrasonic transducers radiating into the air in the frequency range 50-250 kHz”, Arch. Acoust., vol. 17, no. 4, pp. 511–523, Dec. 1992, Accessed: Mar. 04, 2026. [Online]. Available: https://acoustics.ippt.gov.pl/index.php/aa/article/view/1203