@article{SF_1995__51_1_135407,
     author = {R. Padmanabhan and H. Lakser and B. Wolk},
     title = {Varieties of operator semigroups representing partitions.},
     journal = {Semigroup forum},
     pages = {135--152},
     publisher = {mathdoc},
     volume = {51},
     number = {1},
     year = {1995},
     zbl = {0835.20079},
     url = {http://geodesic.mathdoc.fr/item/SF_1995__51_1_135407/}
}