@article{SF_1979__17_134329,
     author = {T. Head},
     title = {Quotient monoids and greatest commutative monoid images of several types.},
     journal = {Semigroup forum},
     pages = {351--364},
     year = {1979},
     volume = {17},
     zbl = {0427.20052},
     url = {http://geodesic.mathdoc.fr/item/SF_1979__17_134329/}
}