1. Adams Robert (1979). Divine command metaethics modified again. The Journal of Religious Ethics 7(1): 66–79
2. Anderson Alan Ross, Belnap Nuel D. (1975). Entailment: The logic of relevance and necessity (Vol. 1). Princeton University Press, Princeton
3. Armstrong David (1997). A world of states of affairs. Cambridge University Press, Cambridge
4. Armstrong David (2003). Truthmakers for modal truths. In: Lillehammer H., Rodriguez-Pereyra G. (eds) Real metaphysics. Routledge, London, pp 12–24
5. Armstrong David (2004). Truth and truthmakers. Cambridge University Press, Cambridge