1. Approximative properties of sets in Hilbert space;Balaganskii;Math. Notes,1982
2. V. S. Balaganskii, L. P. Vlasov, Approximative-geometric properties of sets in Banachspaces, Inst. Math. Mech. Ural Branch Acad. Sci.USSR, Sverdlovsk
3. A proof that every Banach space is subreflexive;Bishop;Bull. Amer. Math. Soc.,1961
4. Local Lipschitz continuity of the metric projectionoperator;Björnestal,1979
5. Weiteste Punkte und nächste Punkte;Blatter;Rev. Roum. Mat. Pur. Appl.,1969