1.
Aaronson J, Ellis D, Leader I. A Note on Transitive Union-Closed Families. Electron. J. Combin. [Internet]. 2021Apr.9 [cited 2026Mar.16];28(2):P2.3. Available from: https://www.combinatorics.org/ojs/index.php/eljc/article/view/v28i2p3