@article{MAN_1968__178_161731,
     author = {J. BLATTER and P.D. MORRIS and D.E. WULBERT},
     title = {Continuity of the {Set-valued} {Metric} {Projection.}},
     journal = {Mathematische Annalen},
     pages = {12--24},
     publisher = {mathdoc},
     volume = {178},
     year = {1968},
     zbl = {0189.42904},
     url = {http://geodesic.mathdoc.fr/item/MAN_1968__178_161731/}
}