Dredge-up effects in galactic and magellanic planetary nebulae R. D.D. Costa, J.A. de Freitas Pacheco and T. P. Idiart Astron. Astrophys. Suppl. Ser., 145 3 (2000) 467-472 Published online: 15 September 2000 DOI: 10.1051/aas:2000252