Tang, Jing, Petter Pilesjö, and Andreas Persson. “Estimating Slope from Raster Data – a Test of Eight Algorithms at Different Resolutions in Flat and Steep Terrain”. Geodesy and Cartography 39, no. 2 (June 28, 2013): 41-52. Accessed January 9, 2025. https://jest.vgtu.lt/index.php/GAC/article/view/4060.