Shary, Peter A., Larisa S. Sharaya, and Andrey V. Mitusov. 2005. “The Problem of Scale-Specific and Scale-Free Approaches in Geomorphometry”. Geografia Fisica E Dinamica Quaternaria 28 (1): 81-101. https://www.gfdq.glaciologia.it/index.php/GFDQ/article/view/379.