Erler 2011, p. 9. Erler, Michael (2011), "Chapter II: Autodidact and student: on the relationship of authority and autonomy in Epicurus and the Epicurean tradition", in Fish, Jeffrey; Sanders, Kirk R. (eds.), Epicurus and the Epicurean Tradition, Cambridge, England: Cambridge University Press, pp. 9–28, ISBN978-0-521-19478-5
Gordon 2013, p. 141. Gordon, Pamela (2013), "Epistulatory Epicureans", in Boter, G. J.; Chaniotis, A.; Coleman, K. M.; de Jong, I. J. F.; Reinhardt, T. (eds.), Epistolary Narratives in Ancient Greek Literature, Mnemosyne: Supplements: Monographs on Greek and Latin Language and Literature, vol. 359, Leiden, The Netherlands: Koninklijke Brill, ISBN978-90-04-25303-2
Carus, Titus Lucretius (July 2008). Of The Nature of Things. Project Gutenberg EBook. Vol. 785. William Ellery Leonard (translator). Project Gutenberg.
Book VI, Section Extraordinary and Paradoxical Telluric Phenomena, Line 9549–9560
C, Yapijakis (2009). "Hippocrates of Kos, the father of clinical medicine, and Asclepiades of Bithynia, the father of molecular medicine. Review". In Vivo. 23 (4): 507–14. PMID19567383.
The only fragment in Greek about this central notion is from the Oenoanda inscription (fr. 54 in Smith's edition). The best known reference is in Lucretius's On the Nature of Things, 2.251.