@article{SF_1974__9_134063,
     author = {M. Petrich},
     title = {Introduction to {Semigroups} {(Book} {Review} by {A.} {H.} {Clifford).}},
     journal = {Semigroup forum},
     pages = {88--94},
     publisher = {mathdoc},
     volume = {9},
     year = {1974},
     url = {http://geodesic.mathdoc.fr/item/SF_1974__9_134063/}
}