@article{SF_1976__12_134188,
     author = {A. Alexander Selden},
     title = {On the closure of bisimple w-semigroups.},
     journal = {Semigroup forum},
     pages = {373--379},
     year = {1976},
     volume = {12},
     zbl = {0338.22003},
     url = {http://geodesic.mathdoc.fr/item/SF_1976__12_134188/}
}