1. Armstrong, D. M. (1978). Universals and scientific realism (2 vols.). Cambridge: Cambridge University Press.
2. Armstrong, D. M. (1997). A world of states of affairs. Cambridge: Cambridge University Press.
3. Armstrong, D. M. (2009). Questions about states of affairs. In M. Reicher (Ed.), States of affairs (pp. 39–50). Berlin: De Gruyter.
4. Beebee, H., & Dodd, J. (2005). Introduction. In H. Beebee & J. Dodd (Eds.), Truthmakers: The contemporary debate (pp. 1–16). Oxford: Oxford University Press.
5. Bigelow, J. (1988). The reality of numbers. Oxford: Clarendon Press.