TRAN VAN AN; NGUYEN VAN DUNG. $ls$-Ponomarev-systems and compact images of locally separable metric spaces. Methods of Functional Analysis and Topology, [S. l.], v. 15, n. 4, p. 391–400, 2009. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/433. Acesso em: 16 dec. 2025.