@article{SF_1980__19_134389,
     author = {M.G. Mogilevskii},
     title = {Order relations on symmetric semigroups of transformations and on their homomorphic images.},
     journal = {Semigroup forum},
     pages = {283--306},
     year = {1980},
     volume = {19},
     zbl = {0444.20060},
     url = {http://geodesic.mathdoc.fr/item/SF_1980__19_134389/}
}