BALCERZAK, A., et al. “Practical Possibilities of More Accurate Velocity Measurements of Ultrasonic Waves in Liquids by Means of the Resonator Method”. Archives of Acoustics, vol. 18, no. 4, May 2014, pp. 539-51, https://acoustics3.ippt.pan.pl/index.php/aa/article/view/1162.