@article{SF_1985__31_134749,
     author = {R.J. Koch and B.L. Madison},
     title = {Relations on the lattice of congruences of a regular semigroup.},
     journal = {Semigroup forum},
     pages = {227--234},
     publisher = {mathdoc},
     volume = {31},
     year = {1985},
     zbl = {0549.20044},
     url = {http://geodesic.mathdoc.fr/item/SF_1985__31_134749/}
}