@article{JRAM_1969__234_150904,
     author = {David A. Sprecher},
     title = {On the existence of best approximations and representations in several variables.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {152--162},
     publisher = {mathdoc},
     volume = {234},
     year = {1969},
     zbl = {0167.04701},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1969__234_150904/}
}