@article{GDZPPN002219522,
title = {Symmetrization of Functions in Sobolev Spaces and The Isoperimetric Inequality.},
journal = {Manuscripta mathematica},
volume = {18},
year = {1976},
pages = {215-236},
zbl = {0365.46031},
url = {http://dml.mathdoc.fr/item/GDZPPN002219522}
}
Hildén, Keijo. Symmetrization of Functions in Sobolev Spaces and The Isoperimetric Inequality.. Manuscripta mathematica, Tome 18 (1976) pp. 215-236. http://gdmltest.u-ga.fr/item/GDZPPN002219522/