1. Linear spaces and approximation theory;Buck,1959
2. Zero sets for continuous functions;Buck,1960
3. Inclusion theorems for the minimal distance in rational Tschebyscheff approximation with several variables;Collatz,1965
4. On Haar's theorem concerning Chebyshev approximation problems having unique solutions;Mairhuber,1956
5. On the unicity of solutions of best approximation;Schoenberg;Ann. Mat. Pura Appl.,1961