@article{SIGMA_2009_5_a101,
     author = {Piotr Mormul},
     title = {Singularity {Classes} of {Special} {2-Flags}},
     journal = {Symmetry, integrability and geometry: methods and applications},
     year = {2009},
     volume = {5},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SIGMA_2009_5_a101/}
}