@article{JRAM_1986__368_152836,
     author = {Kenneth R. Davidson and S.C. Power},
     title = {Best approximation in {C*-algebras.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {43--62},
     publisher = {mathdoc},
     volume = {368},
     year = {1986},
     zbl = {0579.46038},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1986__368_152836/}
}