Reliability and validity of the Adolescent Stress Questionnaire in a sample of European adolescents - the HELENA study - De Vriendt, Tineke; Clays, Els; Moreno, Luis A.; Bergman, Patrick; Vicente-Rodriguez, German; Nagy, Eniko; Dietrich, Sabine; Manios, Yannis; De Henauw, Stefaan;HELENA Study Grp (Bmc Public Health, 2011)