MIŠEIKIS, Feliksas. Approximation of characteristic functions in Rk spaces. Lietuvos matematikos rinkinys, [S. l.], v. 38, n. II, p. 514–516 , 1998. DOI: 10.15388/LMD.1998.37971. Disponível em: https://journals.vu.lt./LMR/article/view/37971. Acesso em: 19 apr. 2025.