@article{SF_1980__19_134385,
     author = {W. Ruppert},
     title = {The structure of semitopological monoids defined on compact connected 3-manifolds.},
     journal = {Semigroup forum},
     pages = {219--246},
     publisher = {mathdoc},
     volume = {19},
     year = {1980},
     zbl = {0435.22003},
     url = {http://geodesic.mathdoc.fr/item/SF_1980__19_134385/}
}