@article{SF_1979__17_134317,
     author = {G.J. Sz\'ekely},
     title = {Algebraic dimension of semigroups with application to invariant measures.},
     journal = {Semigroup forum},
     pages = {185--187},
     publisher = {mathdoc},
     volume = {17},
     year = {1979},
     zbl = {0407.22001},
     url = {http://geodesic.mathdoc.fr/item/SF_1979__17_134317/}
}