@article{GDZPPN002476045,
title = {The Extension Problem for Functions Invariant under a Group.},
journal = {Monatshefte f\"ur Mathematik},
volume = {72},
year = {1968},
pages = {118-132},
zbl = {0159.53001},
url = {http://dml.mathdoc.fr/item/GDZPPN002476045}
}
Chang, B.-Ch.; Smith, J.W. The Extension Problem for Functions Invariant under a Group.. Monatshefte für Mathematik, Tome 72 (1968) pp. 118-132. http://gdmltest.u-ga.fr/item/GDZPPN002476045/