Baltes, Paul B. Center for Lifespan Psychology, Max Planck Institute for Human Development, Max Planck Society; Max Planck Institute for Human Development, Max Planck Society;
Freund, A. M., & Baltes, P. B. (2003). Strategien guten Alterns. In H. Förstl (Ed.), Lehrbuch der Gerontopsychiatrie und -psychotherapie: Grundlagen - Klinik - Therapie (2nd., ext. and upd. ed., pp. 4-10). Stuttgart: Thieme.