@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/