@article{SF_1979__17_134323,
     author = {S. Subbiah and K. jr. Magill},
     title = {Semigroups with exactly three regular ...-classes.},
     journal = {Semigroup forum},
     pages = {279--281},
     publisher = {mathdoc},
     volume = {17},
     year = {1979},
     zbl = {0408.20051},
     url = {http://geodesic.mathdoc.fr/item/SF_1979__17_134323/}
}