@article{701158,
     title = {On the singlevaluedness and differentiation of metric projections},
     booktitle = {Abstracta. 7th Winter School on Abstract Analysis},
     series = {GDML\_Books},
     publisher = {Czechoslovak Academy of Sciences},
     address = {Praha},
     year = {1979},
     pages = {104-105},
     url = {http://dml.mathdoc.fr/item/701158}
}

Zajíček, L. On the singlevaluedness and differentiation of metric projections, dans Abstracta. 7th Winter School on Abstract Analysis, GDML_Books,  (1979), pp. 104-105. http://gdmltest.u-ga.fr/item/701158/