@article{SF_1984__28_134663,
     author = {M.S. Putcha},
     title = {Algebraic monoids with a dense group of units.},
     journal = {Semigroup forum},
     pages = {365--370},
     year = {1984},
     volume = {28},
     zbl = {0524.20044},
     url = {http://geodesic.mathdoc.fr/item/SF_1984__28_134663/}
}