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2. and ?Methodological Challenges in Cross-National Research.? In and (eds.), The Adolescent Experience: European and American Adolescents in the 1990s. Mahwah, N.J.: Erlbaum, 1999.
3. and Sportkultur und jugendliches Selbstkonzept [Sports culture and youthful self-concept]. Weinheim, Germany: Juventa, 1997.
4. and ?Soziale Ungleichheit, Sportengagement und psychosoziales Befinden im Jugendalter? [Social inequality, sports engagement, and psychosocial health in adolescence]. In and (eds.), Armut im Jugendalter [Poverty in adolescence]. Weinheim, Germany: Juventa, 1998.