1. Agar, Nicholas. 2010. Humanity’s end: Why we should reject radical enhancement. Cambridge, MA: MIT Press.
2. ———. 2014. Truly human enhancement: A philosophical defense of limits. Cambridge, MA: MIT Press.
3. Anderson, Ryan, and Christopher Tollefsen. 2008. Biotech enhancement and natural law. The New Atlantis 20: 79–103.
4. Aquinas, Thomas. 1948. Summa theologiae. Vol. 5. Trans. Fathers of the English Dominican Province. New York: Benziger Bros.
5. ———. 1953. The division and methods of the sciences. Trans. Armand Maurer. Toronto: Pontifical Institute of Mediaeval Studies.