References
- [1] Grzegorz Bancerek. The ordinal numbers. Formalized Mathematics, 1(1):91-96, 1990.
- [2] Andrzej Trybulec. Enumerated sets. Formalized Mathematics, 1(1):25-34, 1990.
- [3] Andrzej Trybulec. On the sets inhabited by numbers. Formalized Mathematics, 11(4):341-347, 2003.
- [4] Zinaida Trybulec. Properties of subsets. Formalized Mathematics, 1(1):67-71, 1990.