Near-Tc second-harmonic emission in high-density bulk MgB2 at microwave frequency A. Agliolo Gallitto, G. Bonsignore, G. Giunchi and M. Li Vigni Eur. Phys. J. B, 51 4 (2006) 537-542 Published online: 28 June 2006 DOI: 10.1140/epjb/e2006-00260-4