1. Abelard P. The glosses of Peter Abailard on Porphyry. In: R McKeon (ed.), Selections from Medieval philosophers. 1. Augustine to Albert the Great. New York: Scribner’s (1929), pp. 208–258.
2. Academy of Natural Sciences of Drexel University. Darwin’s chair. https://ansp.org/exhibits/online-exhibits/stories/darwins-chair/, undated. Accessed 5 June 2020 and 9 October 2020.
3. Ferrante Imperato (Napoli, 1550–1625) e il suo contributo alla storia della geologia.;Geologica Romana,1981