@article{SF_1987__36_134900,
     author = {S.K. Stein},
     title = {Semigroups satisfying xy = yg (x,y)x.},
     journal = {Semigroup forum},
     pages = {249--252},
     publisher = {mathdoc},
     volume = {36},
     year = {1987},
     zbl = {0619.20039},
     url = {http://geodesic.mathdoc.fr/item/SF_1987__36_134900/}
}