1. Armstrong, D. M. (1978). Universals and scientific realism. Cambridge University Press.
2. Armstrong, D. M. (1989). Universals: An opinionated introduction. Westview Press.
3. Armstrong, D. M. (1997). A world of states of affairs. Cambridge University Press.
4. Audi, P. (2019). Partial resemblance and property immanence. Nous, 53(4), 884–903.
5. Bealer, G. (1981). Foundations without sets. American Philosophical Quarterly, 18(4), 347–353.