Rings in the haloes of planetary nebulae R. L. M. Corradi, P. Sánchez-Blázquez, G. Mellema, C. Giammanco and H. E. Schwarz A&A, 424 1 (2004) 197 Published online: 17 August 2004 DOI: 10.1051/0004-6361:20034420e