@article{NUMA_1969__13_131910,
     author = {M.R. OSBORNE and G.A. WATSON},
     title = {On {Estimating} {Best} {Approximations} of {Functions} {Defined} by {Differential} {Equations.}},
     journal = {Numerische Mathematik},
     pages = {199--206},
     publisher = {mathdoc},
     volume = {13},
     year = {1969},
     zbl = {0174.47302},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1969__13_131910/}
}