@article{SF_1984__28_134667, author = {K. Ahre}, title = {On the closure of {B'} [o,....).}, journal = {Semigroup forum}, pages = {377--378}, year = {1984}, volume = {28}, zbl = {0527.22002}, url = {http://geodesic.mathdoc.fr/item/SF_1984__28_134667/} }