@article{SF_1981__23_134506,
     author = {B.M. Schein},
     title = {On two papers of {B.M.} {Schein.}},
     journal = {Semigroup forum},
     pages = {87--88},
     publisher = {mathdoc},
     volume = {23},
     year = {1981},
     zbl = {0473.20043},
     url = {http://geodesic.mathdoc.fr/item/SF_1981__23_134506/}
}