@article{SF_1970__1_133789,
     author = {H.R.K. Iyengar},
     title = {An example of a semigroup where a {D-class} is a subsemigroup but not bisimple.},
     journal = {Semigroup forum},
     pages = {182--183},
     publisher = {mathdoc},
     volume = {1},
     year = {1970},
     zbl = {0207.03103},
     url = {http://geodesic.mathdoc.fr/item/SF_1970__1_133789/}
}