@article{10_4064_cm_79_2_185_191,
     author = {George Gr\"atzer and Friedrich Wehrung},
     title = {Flat semilattices},
     journal = {Colloquium Mathematicum},
     pages = {185--191},
     publisher = {mathdoc},
     volume = {79},
     number = {2},
     year = {1999},
     doi = {10.4064/cm-79-2-185-191},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/cm-79-2-185-191/}
}