@article{NUMA_1987__51_133211,
     author = {H. Sp\"ath and G.A. Watson},
     title = {On {Orthogonal} {Linear} ...1 {Approximation.}},
     journal = {Numerische Mathematik},
     pages = {531--544},
     publisher = {mathdoc},
     volume = {51},
     year = {1987},
     zbl = {0633.65010},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1987__51_133211/}
}