@article{JRAM_1988__384_153002,
     author = {John E. Brothers and William P. Ziemer},
     title = {Minimal rearrangements of {Sobolev} functions.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {153--179},
     year = {1988},
     volume = {384},
     zbl = {0633.46030},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1988__384_153002/}
}