@article{SF_1986__35_134876,
     author = {D.R. Brown and Rs.S. Houston},
     title = {Cancellative semigroups on manifolds.},
     journal = {Semigroup forum},
     pages = {279--302},
     year = {1986},
     volume = {35},
     zbl = {0626.22001},
     url = {http://geodesic.mathdoc.fr/item/SF_1986__35_134876/}
}