@article{GDZPPN001171097,
title = {Perturbations of Best Approximation Problems.},
journal = {Numerische Mathematik},
volume = {21},
year = {1973},
pages = {63-69},
zbl = {0264.65009},
url = {http://dml.mathdoc.fr/item/GDZPPN001171097}
}
Anselone, Philip M.; Davis, Joel. Perturbations of Best Approximation Problems.. Numerische Mathematik, Tome 21 (1973) pp. 63-69. http://gdmltest.u-ga.fr/item/GDZPPN001171097/