@article{ADM_2007_2_a10,
     author = {Anatoliy P. Petravchuk and Oleksandr G. Iena},
     title = {On closed rational functions in several variables},
     journal = {Algebra and discrete mathematics},
     pages = {115--124},
     year = {2007},
     number = {2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ADM_2007_2_a10/}
}