@article{SF_1987__36_134902,
     author = {J. Ahsan},
     title = {Monoids characterized by their quasi-injective {S-systems.}},
     journal = {Semigroup forum},
     pages = {285--292},
     publisher = {mathdoc},
     volume = {36},
     year = {1987},
     zbl = {0625.20057},
     url = {http://geodesic.mathdoc.fr/item/SF_1987__36_134902/}
}