@article{GDZPPN002087561, title = {Invariant Rational Functions and a Problem of Steenrod.}, journal = {Inventiones mathematicae}, volume = {9}, year = {1969}, pages = {148-158}, zbl = {0186.07601}, url = {http://dml.mathdoc.fr/item/GDZPPN002087561} }
SWAN, R.G. Invariant Rational Functions and a Problem of Steenrod.. Inventiones mathematicae, Tome 9 (1969) pp. 148-158. http://gdmltest.u-ga.fr/item/GDZPPN002087561/