@article{SF_1974__9_134089,
     author = {J.E. Ault},
     title = {Semigroups with bisimple and simple w-subsemigroups.},
     journal = {Semigroup forum},
     pages = {318--333},
     year = {1974},
     volume = {9},
     zbl = {0298.20057},
     url = {http://geodesic.mathdoc.fr/item/SF_1974__9_134089/}
}