@article{SF_1992__44_1_135126,
     author = {D.M. Davenport},
     title = {On power commutative  semigroups.},
     journal = {Semigroup forum},
     pages = {9--20},
     publisher = {mathdoc},
     volume = {44},
     number = {1},
     year = {1992},
     zbl = {0746.20033},
     url = {http://geodesic.mathdoc.fr/item/SF_1992__44_1_135126/}
}