Near-Tc second-harmonic emission in high-density bulk MgB2 at microwave frequencyA. Agliolo Gallitto, G. Bonsignore, G. Giunchi and M. Li VigniEur. Phys. J. B, 51 4 (2006) 537-542DOI: https://doi.org/10.1140/epjb/e2006-00260-4