@article{SF_1986__33_134818,
     author = {F. Otto},
     title = {On two problems related to cancellativity.},
     journal = {Semigroup forum},
     pages = {331--356},
     publisher = {mathdoc},
     volume = {33},
     year = {1986},
     zbl = {0584.20046},
     url = {http://geodesic.mathdoc.fr/item/SF_1986__33_134818/}
}