@article{AL_2013_52_4_a1,
     author = {V. N. Zhelyabin and A. A. Popov and I. P. Shestakov},
     title = {The coordinate ring of an $n$-dimensional sphere and some examples of differentially simple algebras},
     journal = {Algebra i logika},
     pages = {416--434},
     publisher = {mathdoc},
     volume = {52},
     number = {4},
     year = {2013},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_2013_52_4_a1/}
}