A. El-Ashmawy, D. K. L. . “Mathematical Digital Terrain Model (DTM) Data for Testing DTM Generation Methodologies and Software”. American Scientific Research Journal for Engineering, Technology, and Sciences, vol. 76, no. 1, Feb. 2021, pp. 239-52, https://asrjetsjournal.org/index.php/American_Scientific_Journal/article/view/6640.