Understanding bullying as a significant predictor of posttraumatic stress symptoms in adolescents: insights from clinical samples in Norway, The Netherlands and Germany. - Sachser, Cedric; Kooij, Lieke H.; Keller, Jacob; Eilers, Rebekka; Jensen, Tine K.; Lindauer, Ramon J. L.; Ormhaug, Silje M.; Pfeiffer, Elisa; Rosner, Rita; Skar, Ane-Marthe Solheim; Birkeland, Marianne S. (European Journal of Psychotraumatology, 2025)