@article{MM2_1996__90_2_156192,
     author = {Ignacio Sols and Luis Giraldo},
     title = {On the sectional irregularity of congruences.},
     journal = {Manuscripta mathematica},
     pages = {239--266},
     publisher = {mathdoc},
     volume = {90},
     number = {2},
     year = {1996},
     zbl = {0898.14016},
     url = {http://geodesic.mathdoc.fr/item/MM2_1996__90_2_156192/}
}