@article{GDZPPN002332485,
title = {A W1,p-Estimate for Solutions to Mixed Boundary Value Problems for Second Order Elliptic Differential Equtions.},
journal = {Mathematische Annalen},
volume = {283},
year = {1989},
pages = {679-688},
zbl = {0646.35024},
url = {http://dml.mathdoc.fr/item/GDZPPN002332485}
}
Gröger, Konrad. A W1,p-Estimate for Solutions to Mixed Boundary Value Problems for Second Order Elliptic Differential Equtions.. Mathematische Annalen, Tome 283 (1989) pp. 679-688. http://gdmltest.u-ga.fr/item/GDZPPN002332485/