Subekti, Henk, et al. “ANALYSIS OF CEMENTING WELLS X-1 and Y-1 USING MULTIFUNCTION ULTRASONIC IMAGING LOGGING TOOL”. Journal of Petroleum and Geothermal Technology, vol. 4, no. 2, Nov. 2023, pp. 62-70, doi:10.31315/jpgt.v4i2.10919.