@article{SF_1995__50_3_135382,
     author = {R.Z. Goldstein and P.A. Cummings},
     title = {Solvable word problems in semigroups.},
     journal = {Semigroup forum},
     pages = {243--246},
     publisher = {mathdoc},
     volume = {50},
     number = {3},
     year = {1995},
     zbl = {0821.20040},
     url = {http://geodesic.mathdoc.fr/item/SF_1995__50_3_135382/}
}