Burenkov, Viktor I.: Extension theory for Sobolev spaces on open sets with Lipschitz boundaries.
(English).
In:
Krbec, Miroslav
and Kufner, Alois (eds.): Nonlinear Analysis, Function Spaces and Applications, Proceedings of the Spring School held in Prague, May 31-June 6, 1998.
Vol. 6.
Czech Academy of Sciences, Mathematical Institute, Praha, 1999.
pp. 1-49