@article{10_4064_cm99_1_5,
     author = {Piotr J\k{e}drzejewicz},
     title = {A note on characterizations of rings of constants
 with respect to derivations},
     journal = {Colloquium Mathematicum},
     pages = {51--53},
     publisher = {mathdoc},
     volume = {99},
     number = {1},
     year = {2004},
     doi = {10.4064/cm99-1-5},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/cm99-1-5/}
}