@article{SF_1984__30_134716,
     author = {H. Grassmann},
     title = {Characters and the structure of finite semigroups.},
     journal = {Semigroup forum},
     pages = {211--220},
     year = {1984},
     volume = {30},
     zbl = {0533.20040},
     url = {http://geodesic.mathdoc.fr/item/SF_1984__30_134716/}
}