GEFFERT, Viliam; POPÉLY, Norbert. Refinement of the Alternating Space Hierarchy. Computing and Informatics, [S. l.], v. 21, n. 6, p. 607–616, 2012. Disponível em: https://www.cai.sk/ojs/index.php/cai/article/view/477. Acesso em: 30 apr. 2025.