@article{MM2_1977__23_154527,
     author = {Vlastimil Pt\'ak},
     title = {Derivations, {Commutators} and the {Radical.}},
     journal = {Manuscripta mathematica},
     pages = {355--362},
     year = {1977},
     volume = {23},
     zbl = {0376.46031},
     url = {http://geodesic.mathdoc.fr/item/MM2_1977__23_154527/}
}