@article{10_4064_cm106_1_9,
     author = {Piotr J/edrzejewicz},
     title = {On rings of constants of derivations
 in two variables in positive characteristic},
     journal = {Colloquium Mathematicum},
     pages = {109--117},
     publisher = {mathdoc},
     volume = {106},
     number = {1},
     year = {2006},
     doi = {10.4064/cm106-1-9},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/cm106-1-9/}
}