Radio-to-gamma-ray monitoring of the narrow-line Seyfert 1 galaxy PMN J0948 + 0022 from 2008 to 2011 - Foschini, L.; Angelakis, E.; Fuhrmann, L.; Ghisellini, G.; Hovatta, T.; Lahteenmaki, A.; Lister, M.; Braito, V.; Gallo, L.; Hamilton, T.; Kino, M.; Komossa, S.; et al. (EDP Sciences, 2012)