David Hume (1826). “The Philosophical Works: Including All the Essays, and Exhibiting the More Important Alterations and Corrections in the Successive Ed. Publ. by the Author”, p.137
David Hume, Eric Steinberg (1992). “An Enquiry Concerning Human Understanding; [with] A Letter from a Gentleman to His Friend in Edinburgh; [and] An Abstract of a Treatise of Human Nature”, p.14, Hackett Publishing
David Hume, Eric Steinberg (1993). “An Enquiry Concerning Human Understanding ; [with] A Letter from a Gentleman to His Friend in Edinburgh ; [and] An Abstract of a Treatise of Human Nature”, p.111, Hackett Publishing