HUDEC, Miroslav. Fuzzy improvement of the SQL. Yugoslav Journal of Operations Research, [S. l.], v. 21, n. 2, p. 239–251, 2011. DOI: 10.2298/YJOR1102239H. Disponível em: https://yujor.erc.fon.bg.ac.rs/index.php/yujor/article/view/317. Acesso em: 26 aug. 2025.