@article{GDZPPN002085704,
title = {Necessary conditions on composition operators acting on Sobolev spaces of fractional order. The critical case 1 ... s ... n/p.},
journal = {Forum mathematicum},
volume = {9},
year = {1997},
pages = {267-302},
zbl = {0898.46032},
url = {http://dml.mathdoc.fr/item/GDZPPN002085704}
}
Sickel, Winfried. Necessary conditions on composition operators acting on Sobolev spaces of fractional order. The critical case 1 ... s ... n/p.. Forum mathematicum, Tome 9 (1997) pp. 267-302. http://gdmltest.u-ga.fr/item/GDZPPN002085704/