@article{MM2_1997__92_3_156262,
     author = {G\'abor Elek},
     title = {Betti numbers and {Euler's} formula for combinatorial foliations.},
     journal = {Manuscripta mathematica},
     pages = {239--248},
     publisher = {mathdoc},
     volume = {92},
     number = {3},
     year = {1997},
     zbl = {0876.57042},
     url = {http://geodesic.mathdoc.fr/item/MM2_1997__92_3_156262/}
}