Perceived Severity of Cyberbullying: Differences and Similarities across Four Countries oleh Benedetta E. Palladino, Ersilia Menesini, Annalaura Nocentini, Piret Luik, Karin Naruskov, Zehra Ucanok, Aysun Dogan, Anja Schultze-Krumbholz, Markus Hess, Herbert Scheithauer