C. J. Misak, Verificationism: Its History and Prospects (New York: Routledge, 1995), p. viii.
Miran Epstein, ch 2 "Introduction to philosophy of science", in Clive Seale, ed, Researching Society and Culture, 3rd edn (London: Sage Publications, 2012), pp. 18–19.
Karl Popper, ch 4, subch "Science: Conjectures and refutations", in Andrew Bailey, ed, First Philosophy: Fundamental Problems and Readings in Philosophy, 2nd edn (Peterborough Ontario: Broadview Press, 2011), pp. 338–42.
Apesar do empirismo radical de Hume, estabelecido perto de 1740, Hume também estava comprometido com o senso comum, e aparentemente não assumiu seu próprio ceticismo, como o problema da indução, tão drasticamente quanto outros mais tarde [Antony G Flew, A Dictionary of Philosophy, rev 2nd edn (Nova Iorque: St Martin's Press, 1984), "Hume", p. 156].
britannica.com
Editors of Encyclopædia Britannica, "Verifiability principle", Encyclopædia Britannica, Website accessed 12 Mar 2014.
