Nearby early-type galaxies with ionized gas - IV. Origin and powering mechanism of the ionized gasF. Annibali, A. Bressan, R. Rampazzo, W. W. Zeilinger, O. Vega and P. PanuzzoA&A, 519 (2010) A40DOI: https://doi.org/10.1051/0004-6361/200913774
