↑Pruyne, John; Jon T. Kilpinen (1996-11-02). "William Morris Davis". Valparaiso University Department of Geography and Meteorology. Diarsipkan dari asli tanggal 2010-08-28. Diakses tanggal 2010-08-18. Davis' contributions cover the separate fields of geography, geology, and meteorology.
↑Chorley, Richard J.; Beckinsale, Robert P.; Dunn, Antony J. (2005) [1973]. "Chapter Twenty-Two". The History of the Study of Landforms. Vol.Volume Two. Taylor & Francis e-Library. hlm.569.