@article{SF_1977__14_186367,
     author = {P.G. Trotter},
     title = {Cancellative simple semigroups and groups.},
     journal = {Semigroup forum},
     pages = {189--198},
     publisher = {mathdoc},
     volume = {14},
     year = {1977},
     zbl = {0359.20046},
     url = {http://geodesic.mathdoc.fr/item/SF_1977__14_186367/}
}