Energetics and electronic properties of BN nanocones with pentagonal rings at their apexes M. P. Machado, P. Piquini and R. Mota Eur. Phys. J. D, 23 1 (2003) 91-93 Published online: 11 February 2003 DOI: 10.1140/epjd/e2003-00040-x