@article{JOLT_2013_23_2_a9,
     author = {Dieter Degrijse},
     title = {On a {Filtration} of the {Second} {Cohomology} of {Nilpotent} {Lie} {Algebras}},
     journal = {Journal of Lie Theory},
     pages = {551--573},
     year = {2013},
     volume = {23},
     number = {2},
     url = {http://geodesic.mathdoc.fr/item/JOLT_2013_23_2_a9/}
}