1. A-sets in complete metric spaces;El'kin;Soviet Math. Doklady,1967
2. Images of Borel sets and k-analytic sets;Freiwald,1970
3. Borel measurable mappings for non-separable metric spaces;Hansell,1969
4. Einbettung metrischer Räume;Kowalski;Arch. Math. Brno,1957