Rings in the haloes of planetary nebulae R. L. M. Corradi, P. Sánchez-Blázquez, G. Mellema, C. Gianmanco and H. E. Schwarz A&A, 417 2 (2004) 637-646 Published online: 19 March 2004 DOI: 10.1051/0004-6361:20034420