@article{SF_1971__3_133862,
     author = {D.B. McAlister},
     title = {Homomorphisms of semigroups of binary relations.},
     journal = {Semigroup forum},
     pages = {185--188},
     publisher = {mathdoc},
     volume = {3},
     year = {1971},
     zbl = {0246.20060},
     url = {http://geodesic.mathdoc.fr/item/SF_1971__3_133862/}
}