@article{SF_1974__6_133983,
     author = {T.E. Hall},
     title = {The partially ordered set of all {J-classes} of a finite semigroup.},
     journal = {Semigroup forum},
     pages = {263--264},
     publisher = {mathdoc},
     volume = {6},
     year = {1974},
     zbl = {0263.06005},
     url = {http://geodesic.mathdoc.fr/item/SF_1974__6_133983/}
}