1. Continuity of the set-valued metric projection;Blatter;Math. Ann.,1968
2. Continuous selections for metric projections;Lazar;J. Functional Analysis,1969
3. Best n-dimensional approximation to sets of functions;Brown,1964
4. Approximation of Functions;Lorentz,1966
5. On Haar's theorem concerning Chebysheff problems having unique solutions;Mairhuber,1956