SCHUMM , S. A., and R. W. LICHTY. “TIME, SPACE, AND CAUSALITY IN GEOMORPHOLOGY”. William Morris Davis – Revista de Geomorfologia 2, no. 1 (April 23, 2021): 1-9. Accessed October 21, 2021. //williammorrisdavis.uvanet.br/index.php/revistageomorfologia/article/view/111.