@article{MS2_1975__36_166409,
     author = {Victor Klee and David Gale},
     title = {Unique reducibility of subsets of commutative topological groups and semigroups.},
     journal = {Mathematica Scandinavica},
     pages = {175--199},
     publisher = {mathdoc},
     volume = {36},
     year = {1975},
     zbl = {0302.20048},
     url = {http://geodesic.mathdoc.fr/item/MS2_1975__36_166409/}
}