BENNETT, Harold; DAVIS, Sheldon; LUTZER, David. A note on $\eta_1$-spaces. Topology Proceedings, [S. l.], v. 59, p. 25–50, 2020. Disponível em: https://www.topologyproceedings.org/index.php/tp/article/view/25. Acesso em: 30 jun. 2026.