@article{CMUC_1982__23_1_a12,
     author = {Trlifaj, Jan},
     title = {$E$-rings and differential polynomials over universal fields},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {159--166},
     publisher = {mathdoc},
     volume = {23},
     number = {1},
     year = {1982},
     mrnumber = {653359},
     zbl = {0509.16014},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1982__23_1_a12/}
}