@article{05296677, title = {Second cohomology and nilpotency class 2.}, journal = {Publications de l'Institut Math\'ematique. Nouvelle S\'erie}, volume = {82(96)}, year = {2007}, pages = {3-10}, doi = {10.2298/PIM0795003C}, zbl = {1186.20034}, language = {en}, url = {http://dml.mathdoc.fr/item/05296677} }
Crvenković, Siniša; Tasić, Vladimir. Second cohomology and nilpotency class 2.. Publications de l'Institut Mathématique. Nouvelle Série, Tome 82(96) (2007) pp. 3-10. doi : 10.2298/PIM0795003C. http://gdmltest.u-ga.fr/item/05296677/