A search for changing-look AGN in the Grossan catalogS. Bianchi, M. Guainazzi, G. Matt, M. Chiaberge, K. Iwasawa, F. Fiore and R. MaiolinoA&A, 442 1 (2005) 185-194DOI: https://doi.org/10.1051/0004-6361:20053389
