@article{PORMA_1969__28_2_115088,
     author = {Kannappan, P.I.},
     title = {Characterizing topology on an {Abelian} semigroup by a functional equation},
     journal = {Portugaliae mathematica},
     pages = {97--101},
     publisher = {mathdoc},
     volume = {28},
     number = {2},
     year = {1969},
     mrnumber = {0285644},
     zbl = {0213.03102},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PORMA_1969__28_2_115088/}
}