@article{SF_1972__4_133898,
     author = {J.D. McKnight and E. Sadowski},
     title = {The kernel of the wreath product of semigroups.},
     journal = {Semigroup forum},
     pages = {232--236},
     year = {1972},
     volume = {4},
     zbl = {0274.20083},
     url = {http://geodesic.mathdoc.fr/item/SF_1972__4_133898/}
}