Gaukroger, S., Descartes' System of Natural Philosophy (Cambridge: Cambridge University Press, 2002), pp. 180–214.
Spencer, J., "'Love and Hatred are Common to the Whole Sensitive Creation': Animal Feeling in the Century before Darwin," in A. Richardson, ed., After Darwin: Animals, Emotions, and the Mind (Amsterdam and New York: Rodopi, 2013), p. 37.