Exact order of Hoffman's error bounds for elliptic quadratic inequalities derived from vector-valued Chebyshev approximation. - Martin Bartelt; Wu Li (Math. Program., 2000)

Lipschitz continuity and Gateaux differentiability of the best approximation operator in vector-valued Chebyshev approximation. - Martin Bartelt; John Swetits (J. Approx. Theory, 2007)

Lipschitz continuity of the best approximation operator in vector-valued Chebyshev approximation. - Martin Bartelt; John Swetits (J. Approx. Theory, 2008)