@article{TAC_2015_30_a26,
     author = {A.R. Garzon and E.M. Vitale},
     title = {On the second cohomology categorical group and a {Hochschild-Serre} 2-exact sequence},
     journal = {Theory and applications of categories},
     pages = {933--984},
     publisher = {mathdoc},
     volume = {30},
     year = {2015},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/TAC_2015_30_a26/}
}