Goodman, N. (1972). A world of individuals. In Problems and projects (pp. 155–172). Bobs-Merrill company.
Quine, W. V. O. (1976b). Implicit definition sustained. In The ways of paradox and other essays (2. enlarged and revised ed., pp. 133–136). Cambridge, MA: Harvard University Press.
Russell, B. (1906). On some difficulties in the theory of transfinite numbers and order types. Proceedings of London Mathematical Society, 4, 29–53.