@article{SF_1993__47_2_135263,
     author = {J. Pym},
     title = {Affine semigroups and second duals.},
     journal = {Semigroup forum},
     pages = {130--132},
     publisher = {mathdoc},
     volume = {47},
     number = {2},
     year = {1993},
     zbl = {0782.22002},
     url = {http://geodesic.mathdoc.fr/item/SF_1993__47_2_135263/}
}