@article{JLT_2004_14_2_JLT_2004_14_2_a5,
     author = {D. D. Pervouchine},
     title = {Hierarchy of {Closures} of {Matrix} {Pencils}},
     journal = {Journal of Lie theory},
     pages = {443--479},
     year = {2004},
     volume = {14},
     number = {2},
     url = {http://geodesic.mathdoc.fr/item/JLT_2004_14_2_JLT_2004_14_2_a5/}
}