@article{MM2_1994__82_1_155925,
     author = {David L. Wehlau},
     title = {When is a {Ring} of {Torus} {Invariants} a {Polynomial} {Ring?}},
     journal = {Manuscripta mathematica},
     pages = {161--170},
     publisher = {mathdoc},
     volume = {82},
     number = {1},
     year = {1994},
     zbl = {0809.14008},
     url = {http://geodesic.mathdoc.fr/item/MM2_1994__82_1_155925/}
}