Can retired galaxies mimic active galaxies? Clues from the Sloan Digital Sky Survey - Stasinska, G; Vale Asari, N; Cid Fernandes, R; Gomes, J. M; Schlickmann, M; Mateus, A; Schoenell, w; Sodré Júnior, Laerte (Monthly Notices of the Royal Astronomical Society, 2008)