@article{SF_1971__3_133858,
     author = {M. Yamada},
     title = {Note on exclusive semigroups.},
     journal = {Semigroup forum},
     pages = {160--167},
     publisher = {mathdoc},
     volume = {3},
     year = {1971},
     zbl = {0237.20055},
     url = {http://geodesic.mathdoc.fr/item/SF_1971__3_133858/}
}