SRINVASA RAO, K., and T. M. SRINVASAN. “An Array Receiver Scheme for Reducing Refraction Induced Artifacts in Ultrasonic Tof Tomography”. Archives of Acoustics, vol. 12, no. 3-4, July 2015, pp. 311-8, https://acoustics3.ippt.pan.pl/index.php/aa/article/view/3100.