Abell 43: longest period planetary nebula nucleus variable J.-E. Solheim, G. Vauclair, A. S. Mukadam, R. Janulis and V. Dobrovolskas A&A, 468 3 (2007) 1057-1061 Published online: 02 May 2007 DOI: 10.1051/0004-6361:20077364