@article{DCG_1989__4_6_131099,
     author = {N. Megiddo},
     title = {On the {Ball} {Spanned} by {Balls.}},
     journal = {Discrete & computational geometry},
     pages = {605--610},
     publisher = {mathdoc},
     volume = {4},
     number = {6},
     year = {1989},
     zbl = {0688.90020},
     url = {http://geodesic.mathdoc.fr/item/DCG_1989__4_6_131099/}
}