@article{SF_1970__1_133790,
     author = {M. Petrich},
     title = {Bibliographical comment.},
     journal = {Semigroup forum},
     pages = {184--184},
     publisher = {mathdoc},
     volume = {1},
     year = {1970},
     zbl = {0206.02504},
     url = {http://geodesic.mathdoc.fr/item/SF_1970__1_133790/}
}