@article{SF_1992__44_1_135153,
     author = {N. Kehayopulu},
     title = {On left regular and left duo poe-semigroups.},
     journal = {Semigroup forum},
     pages = {306--313},
     publisher = {mathdoc},
     volume = {44},
     number = {1},
     year = {1992},
     zbl = {0756.06007},
     url = {http://geodesic.mathdoc.fr/item/SF_1992__44_1_135153/}
}