@article{SF_1979__18_134353,
     author = {B. Pond\'elicek},
     title = {The intersection graph of a simply ordered semigroup.},
     journal = {Semigroup forum},
     pages = {229--234},
     publisher = {mathdoc},
     volume = {18},
     year = {1979},
     zbl = {0419.06008},
     url = {http://geodesic.mathdoc.fr/item/SF_1979__18_134353/}
}