Internet Addictive Behavior in Adolescence: A Cross-Sectional Study in Seven European Countries. - Artemis Tsitsika; Mari Janikian; Tim M. Schoenmakers; Eleni C. Tzavela; Kjartan Ólafsson; Szymon Wójcik; George Florian Macarie; Chara Tzavara; Clive Richardson (Cyberpsychology Behav. Soc. Netw., 2014)