@article{PIM_1979_N_S_26_40_a1,
     author = {Dragan M. Acketa},
     title = {On {The} {Essential} {Flats} {Of} {Geometric} {Lattices}},
     journal = {Publications de l'Institut Math\'ematique},
     pages = {11 },
     publisher = {mathdoc},
     volume = {_N_S_26},
     number = {40},
     year = {1979},
     url = {http://geodesic.mathdoc.fr/item/PIM_1979_N_S_26_40_a1/}
}