Smith, Adam (1872). Black, Joseph; Hutton, James (eds.). The Essays of Adam Smith (6 ed.). London: Alex. Murry & Co. p. 9. Retrieved 21 Jan 2021.
Smith, Adam (1872). Black, Joseph; Hutton, James, eds. The Essays of Adam Smith (6th edición). London: Alex. Murray & Co. pp. 48-51. Consultado el 21 Jan 2021.
Smith, Adam (1872). Black, Joseph; Hutton, James, eds. The Essays of Adam Smith (6 edición). London: Alex. Murry & Co. pp. 56-59. Consultado el 21 Jan 2021.
researchgate.net
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