ZHANG, X.; BUSSCHE, J. V. den; WANG, K.; ZHANG, H.; YANG, X.; FENG, Z. On the Expressivity of ASK Queries in SPARQL. Proceedings of the AAAI Conference on Artificial Intelligence, [S. l.], v. 34, n. 03, p. 3057-3064, 2020. DOI: 10.1609/aaai.v34i03.5700. Disponível em: https://ojs.aaai.org/index.php/AAAI/article/view/5700. Acesso em: 26 feb. 2021.